diff --git a/mypy/typeshed/stdlib/VERSIONS b/mypy/typeshed/stdlib/VERSIONS
index d24aa35faf6e..86e8da78677c 100644
--- a/mypy/typeshed/stdlib/VERSIONS
+++ b/mypy/typeshed/stdlib/VERSIONS
@@ -61,7 +61,7 @@ antigravity: 2.7-
 argparse: 2.7-
 array: 2.7-
 ast: 2.7-
-asynchat: 2.7-
+asynchat: 2.7-3.11
 asyncio: 3.4-
 asyncio.mixins: 3.10-
 asyncio.exceptions: 3.8-
@@ -72,7 +72,7 @@ asyncio.taskgroups: 3.11-
 asyncio.threads: 3.9-
 asyncio.timeouts: 3.11-
 asyncio.trsock: 3.8-
-asyncore: 2.7-
+asyncore: 2.7-3.11
 atexit: 2.7-
 audioop: 2.7-
 base64: 2.7-
@@ -228,7 +228,7 @@ shlex: 2.7-
 shutil: 2.7-
 signal: 2.7-
 site: 2.7-
-smtpd: 2.7-
+smtpd: 2.7-3.11
 smtplib: 2.7-
 sndhdr: 2.7-
 socket: 2.7-
diff --git a/mypy/typeshed/stdlib/_collections_abc.pyi b/mypy/typeshed/stdlib/_collections_abc.pyi
index 352da6cfb331..05b5421c21f3 100644
--- a/mypy/typeshed/stdlib/_collections_abc.pyi
+++ b/mypy/typeshed/stdlib/_collections_abc.pyi
@@ -1,4 +1,5 @@
 import sys
+from abc import abstractmethod
 from types import MappingProxyType
 from typing import (  # noqa: Y022,Y038
     AbstractSet as Set,
@@ -23,11 +24,13 @@ from typing import (  # noqa: Y022,Y038
     MutableMapping as MutableMapping,
     MutableSequence as MutableSequence,
     MutableSet as MutableSet,
+    Protocol,
     Reversible as Reversible,
     Sequence as Sequence,
     Sized as Sized,
     TypeVar,
     ValuesView as ValuesView,
+    runtime_checkable,
 )
 from typing_extensions import final
 
@@ -58,6 +61,8 @@ __all__ = [
     "MutableSequence",
     "ByteString",
 ]
+if sys.version_info >= (3, 12):
+    __all__ += ["Buffer"]
 
 _KT_co = TypeVar("_KT_co", covariant=True)  # Key type covariant containers.
 _VT_co = TypeVar("_VT_co", covariant=True)  # Value type covariant containers.
@@ -79,3 +84,9 @@ class dict_items(ItemsView[_KT_co, _VT_co], Generic[_KT_co, _VT_co]):  # undocum
     if sys.version_info >= (3, 10):
         @property
         def mapping(self) -> MappingProxyType[_KT_co, _VT_co]: ...
+
+if sys.version_info >= (3, 12):
+    @runtime_checkable
+    class Buffer(Protocol):
+        @abstractmethod
+        def __buffer__(self, __flags: int) -> memoryview: ...
diff --git a/mypy/typeshed/stdlib/_ctypes.pyi b/mypy/typeshed/stdlib/_ctypes.pyi
index 4f8de4605d4d..8e8bcbe84bd4 100644
--- a/mypy/typeshed/stdlib/_ctypes.pyi
+++ b/mypy/typeshed/stdlib/_ctypes.pyi
@@ -63,6 +63,8 @@ class _CData(metaclass=_CDataMeta):
     def from_param(cls, obj: Any) -> Self | _CArgObject: ...
     @classmethod
     def in_dll(cls, library: CDLL, name: str) -> Self: ...
+    def __buffer__(self, __flags: int) -> memoryview: ...
+    def __release_buffer__(self, __buffer: memoryview) -> None: ...
 
 class _SimpleCData(Generic[_T], _CData):
     value: _T
diff --git a/mypy/typeshed/stdlib/_typeshed/__init__.pyi b/mypy/typeshed/stdlib/_typeshed/__init__.pyi
index 3c29032b6b0d..5d03142c6d71 100644
--- a/mypy/typeshed/stdlib/_typeshed/__init__.pyi
+++ b/mypy/typeshed/stdlib/_typeshed/__init__.pyi
@@ -2,17 +2,13 @@
 #
 # See the README.md file in this directory for more information.
 
-import array
-import ctypes
-import mmap
-import pickle
 import sys
-from collections.abc import Awaitable, Callable, Iterable, Set as AbstractSet
+from collections.abc import Awaitable, Callable, Iterable, Sequence, Set as AbstractSet, Sized
 from dataclasses import Field
 from os import PathLike
 from types import FrameType, TracebackType
-from typing import Any, AnyStr, ClassVar, Generic, Protocol, TypeVar
-from typing_extensions import Final, Literal, LiteralString, TypeAlias, final
+from typing import Any, AnyStr, ClassVar, Generic, Protocol, TypeVar, overload
+from typing_extensions import Buffer, Final, Literal, LiteralString, TypeAlias, final
 
 _KT = TypeVar("_KT")
 _KT_co = TypeVar("_KT_co", covariant=True)
@@ -227,42 +223,33 @@ class SupportsNoArgReadline(Protocol[_T_co]):
 class SupportsWrite(Protocol[_T_contra]):
     def write(self, __s: _T_contra) -> object: ...
 
-ReadOnlyBuffer: TypeAlias = bytes  # stable
+# Unfortunately PEP 688 does not allow us to distinguish read-only
+# from writable buffers. We use these aliases for readability for now.
+# Perhaps a future extension of the buffer protocol will allow us to
+# distinguish these cases in the type system.
+ReadOnlyBuffer: TypeAlias = Buffer  # stable
 # Anything that implements the read-write buffer interface.
-# The buffer interface is defined purely on the C level, so we cannot define a normal Protocol
-# for it (until PEP 688 is implemented). Instead we have to list the most common stdlib buffer classes in a Union.
-if sys.version_info >= (3, 8):
-    WriteableBuffer: TypeAlias = (
-        bytearray | memoryview | array.array[Any] | mmap.mmap | ctypes._CData | pickle.PickleBuffer
-    )  # stable
-else:
-    WriteableBuffer: TypeAlias = bytearray | memoryview | array.array[Any] | mmap.mmap | ctypes._CData  # stable
-# Same as _WriteableBuffer, but also includes read-only buffer types (like bytes).
-ReadableBuffer: TypeAlias = ReadOnlyBuffer | WriteableBuffer  # stable
-_BufferWithLen: TypeAlias = ReadableBuffer  # not stable  # noqa: Y047
-
-# Anything that implements the read-write buffer interface, and can be sliced/indexed.
-SliceableBuffer: TypeAlias = bytes | bytearray | memoryview | array.array[Any] | mmap.mmap
-IndexableBuffer: TypeAlias = bytes | bytearray | memoryview | array.array[Any] | mmap.mmap
-# https://github.com/python/typeshed/pull/9115#issuecomment-1304905864
-# Post PEP 688, they should be rewritten as such:
-# from collections.abc import Sequence
-# from typing import Sized, overload
-# class SliceableBuffer(Protocol):
-#     def __buffer__(self, __flags: int) -> memoryview: ...
-#     def __getitem__(self, __slice: slice) -> Sequence[int]: ...
-# class IndexableBuffer(Protocol):
-#     def __buffer__(self, __flags: int) -> memoryview: ...
-#     def __getitem__(self, __i: int) -> int: ...
-# class SupportsGetItemBuffer(SliceableBuffer, IndexableBuffer, Protocol):
-#     def __buffer__(self, __flags: int) -> memoryview: ...
-#     def __contains__(self, __x: Any) -> bool: ...
-#     @overload
-#     def __getitem__(self, __slice: slice) -> Sequence[int]: ...
-#     @overload
-#     def __getitem__(self, __i: int) -> int: ...
-# class SizedBuffer(Sized, Protocol):  # instead of _BufferWithLen
-#     def __buffer__(self, __flags: int) -> memoryview: ...
+WriteableBuffer: TypeAlias = Buffer
+# Same as WriteableBuffer, but also includes read-only buffer types (like bytes).
+ReadableBuffer: TypeAlias = Buffer  # stable
+
+class SliceableBuffer(Buffer, Protocol):
+    def __getitem__(self, __slice: slice) -> Sequence[int]: ...
+
+class IndexableBuffer(Buffer, Protocol):
+    def __getitem__(self, __i: int) -> int: ...
+
+class SupportsGetItemBuffer(SliceableBuffer, IndexableBuffer, Protocol):
+    def __contains__(self, __x: Any) -> bool: ...
+    @overload
+    def __getitem__(self, __slice: slice) -> Sequence[int]: ...
+    @overload
+    def __getitem__(self, __i: int) -> int: ...
+
+class SizedBuffer(Sized, Buffer, Protocol): ...
+
+# for compatibility with third-party stubs that may use this
+_BufferWithLen: TypeAlias = SizedBuffer  # not stable  # noqa: Y047
 
 ExcInfo: TypeAlias = tuple[type[BaseException], BaseException, TracebackType]
 OptExcInfo: TypeAlias = ExcInfo | tuple[None, None, None]
diff --git a/mypy/typeshed/stdlib/argparse.pyi b/mypy/typeshed/stdlib/argparse.pyi
index 1e956069314b..c986b9cdb082 100644
--- a/mypy/typeshed/stdlib/argparse.pyi
+++ b/mypy/typeshed/stdlib/argparse.pyi
@@ -2,7 +2,7 @@ import sys
 from collections.abc import Callable, Generator, Iterable, Sequence
 from re import Pattern
 from typing import IO, Any, Generic, NewType, NoReturn, Protocol, TypeVar, overload
-from typing_extensions import Literal, TypeAlias
+from typing_extensions import Literal, Self, TypeAlias
 
 __all__ = [
     "ArgumentParser",
@@ -236,11 +236,19 @@ class HelpFormatter:
     _current_indent: int
     _level: int
     _action_max_length: int
-    _root_section: Any
-    _current_section: Any
+    _root_section: _Section
+    _current_section: _Section
     _whitespace_matcher: Pattern[str]
     _long_break_matcher: Pattern[str]
-    _Section: type[Any]  # Nested class
+
+    class _Section:
+        formatter: HelpFormatter
+        heading: str | None
+        parent: Self | None
+        items: list[tuple[Callable[..., str], Iterable[Any]]]
+        def __init__(self, formatter: HelpFormatter, parent: Self | None, heading: str | None = None) -> None: ...
+        def format_help(self) -> str: ...
+
     def __init__(self, prog: str, indent_increment: int = 2, max_help_position: int = 24, width: int | None = None) -> None: ...
     def _indent(self) -> None: ...
     def _dedent(self) -> None: ...
@@ -249,16 +257,16 @@ class HelpFormatter:
     def end_section(self) -> None: ...
     def add_text(self, text: str | None) -> None: ...
     def add_usage(
-        self, usage: str | None, actions: Iterable[Action], groups: Iterable[_ArgumentGroup], prefix: str | None = None
+        self, usage: str | None, actions: Iterable[Action], groups: Iterable[_MutuallyExclusiveGroup], prefix: str | None = None
     ) -> None: ...
     def add_argument(self, action: Action) -> None: ...
     def add_arguments(self, actions: Iterable[Action]) -> None: ...
     def format_help(self) -> str: ...
     def _join_parts(self, part_strings: Iterable[str]) -> str: ...
     def _format_usage(
-        self, usage: str | None, actions: Iterable[Action], groups: Iterable[_ArgumentGroup], prefix: str | None
+        self, usage: str | None, actions: Iterable[Action], groups: Iterable[_MutuallyExclusiveGroup], prefix: str | None
     ) -> str: ...
-    def _format_actions_usage(self, actions: Iterable[Action], groups: Iterable[_ArgumentGroup]) -> str: ...
+    def _format_actions_usage(self, actions: Iterable[Action], groups: Iterable[_MutuallyExclusiveGroup]) -> str: ...
     def _format_text(self, text: str) -> str: ...
     def _format_action(self, action: Action) -> str: ...
     def _format_action_invocation(self, action: Action) -> str: ...
diff --git a/mypy/typeshed/stdlib/array.pyi b/mypy/typeshed/stdlib/array.pyi
index 38a815b584cd..8b003503bc9b 100644
--- a/mypy/typeshed/stdlib/array.pyi
+++ b/mypy/typeshed/stdlib/array.pyi
@@ -80,5 +80,7 @@ class array(MutableSequence[_T], Generic[_T]):
     def __rmul__(self, __value: int) -> array[_T]: ...
     def __copy__(self) -> array[_T]: ...
     def __deepcopy__(self, __unused: Any) -> array[_T]: ...
+    def __buffer__(self, __flags: int) -> memoryview: ...
+    def __release_buffer__(self, __buffer: memoryview) -> None: ...
 
 ArrayType = array
diff --git a/mypy/typeshed/stdlib/asyncio/__init__.pyi b/mypy/typeshed/stdlib/asyncio/__init__.pyi
index c4e000d2323a..2ce066cac982 100644
--- a/mypy/typeshed/stdlib/asyncio/__init__.pyi
+++ b/mypy/typeshed/stdlib/asyncio/__init__.pyi
@@ -1,5 +1,5 @@
 import sys
-from collections.abc import Coroutine, Generator
+from collections.abc import Awaitable, Coroutine, Generator
 from typing import Any, TypeVar
 from typing_extensions import TypeAlias
 
@@ -36,6 +36,8 @@ _T = TypeVar("_T")
 
 # Aliases imported by multiple submodules in typeshed
 if sys.version_info >= (3, 12):
+    _AwaitableLike: TypeAlias = Awaitable[_T]
     _CoroutineLike: TypeAlias = Coroutine[Any, Any, _T]
 else:
+    _AwaitableLike: TypeAlias = Generator[Any, None, _T] | Awaitable[_T]
     _CoroutineLike: TypeAlias = Generator[Any, None, _T] | Coroutine[Any, Any, _T]
diff --git a/mypy/typeshed/stdlib/asyncio/base_events.pyi b/mypy/typeshed/stdlib/asyncio/base_events.pyi
index 9dcefc8b3308..fd765fdb0614 100644
--- a/mypy/typeshed/stdlib/asyncio/base_events.pyi
+++ b/mypy/typeshed/stdlib/asyncio/base_events.pyi
@@ -1,13 +1,13 @@
 import ssl
 import sys
 from _typeshed import FileDescriptorLike, ReadableBuffer, WriteableBuffer
-from asyncio import _CoroutineLike
+from asyncio import _AwaitableLike, _CoroutineLike
 from asyncio.events import AbstractEventLoop, AbstractServer, Handle, TimerHandle, _TaskFactory
 from asyncio.futures import Future
 from asyncio.protocols import BaseProtocol
 from asyncio.tasks import Task
 from asyncio.transports import BaseTransport, DatagramTransport, ReadTransport, SubprocessTransport, Transport, WriteTransport
-from collections.abc import Awaitable, Callable, Generator, Iterable, Sequence
+from collections.abc import Callable, Iterable, Sequence
 from contextvars import Context
 from socket import AddressFamily, SocketKind, _Address, _RetAddress, socket
 from typing import IO, Any, TypeVar, overload
@@ -64,11 +64,7 @@ class Server(AbstractServer):
 
 class BaseEventLoop(AbstractEventLoop):
     def run_forever(self) -> None: ...
-    # Can't use a union, see mypy issue  # 1873.
-    @overload
-    def run_until_complete(self, future: Generator[Any, None, _T]) -> _T: ...
-    @overload
-    def run_until_complete(self, future: Awaitable[_T]) -> _T: ...
+    def run_until_complete(self, future: _AwaitableLike[_T]) -> _T: ...
     def stop(self) -> None: ...
     def is_running(self) -> bool: ...
     def is_closed(self) -> bool: ...
diff --git a/mypy/typeshed/stdlib/asyncio/events.pyi b/mypy/typeshed/stdlib/asyncio/events.pyi
index 4776aaa5df0c..11112bb2e87d 100644
--- a/mypy/typeshed/stdlib/asyncio/events.pyi
+++ b/mypy/typeshed/stdlib/asyncio/events.pyi
@@ -2,13 +2,13 @@ import ssl
 import sys
 from _typeshed import FileDescriptorLike, ReadableBuffer, StrPath, Unused, WriteableBuffer
 from abc import ABCMeta, abstractmethod
-from collections.abc import Awaitable, Callable, Coroutine, Generator, Sequence
+from collections.abc import Callable, Coroutine, Generator, Sequence
 from contextvars import Context
 from socket import AddressFamily, SocketKind, _Address, _RetAddress, socket
 from typing import IO, Any, Protocol, TypeVar, overload
 from typing_extensions import Literal, Self, TypeAlias
 
-from . import _CoroutineLike
+from . import _AwaitableLike, _CoroutineLike
 from .base_events import Server
 from .futures import Future
 from .protocols import BaseProtocol
@@ -113,13 +113,8 @@ class AbstractEventLoop:
     slow_callback_duration: float
     @abstractmethod
     def run_forever(self) -> None: ...
-    # Can't use a union, see mypy issue  # 1873.
-    @overload
     @abstractmethod
-    def run_until_complete(self, future: Generator[Any, None, _T]) -> _T: ...
-    @overload
-    @abstractmethod
-    def run_until_complete(self, future: Awaitable[_T]) -> _T: ...
+    def run_until_complete(self, future: _AwaitableLike[_T]) -> _T: ...
     @abstractmethod
     def stop(self) -> None: ...
     @abstractmethod
diff --git a/mypy/typeshed/stdlib/asyncio/tasks.pyi b/mypy/typeshed/stdlib/asyncio/tasks.pyi
index 478f19055465..d8c101f281fc 100644
--- a/mypy/typeshed/stdlib/asyncio/tasks.pyi
+++ b/mypy/typeshed/stdlib/asyncio/tasks.pyi
@@ -1,6 +1,6 @@
 import concurrent.futures
 import sys
-from collections.abc import Awaitable, Generator, Iterable, Iterator
+from collections.abc import Awaitable, Coroutine, Generator, Iterable, Iterator
 from types import FrameType
 from typing import Any, Generic, TextIO, TypeVar, overload
 from typing_extensions import Literal, TypeAlias
@@ -275,6 +275,11 @@ else:
     ) -> tuple[set[Task[_T]], set[Task[_T]]]: ...
     async def wait_for(fut: _FutureLike[_T], timeout: float | None, *, loop: AbstractEventLoop | None = None) -> _T: ...
 
+if sys.version_info >= (3, 12):
+    _TaskCompatibleCoro: TypeAlias = Coroutine[Any, Any, _T_co]
+else:
+    _TaskCompatibleCoro: TypeAlias = Generator[_TaskYieldType, None, _T_co] | Awaitable[_T_co]
+
 # mypy and pyright complain that a subclass of an invariant class shouldn't be covariant.
 # While this is true in general, here it's sort-of okay to have a covariant subclass,
 # since the only reason why `asyncio.Future` is invariant is the `set_result()` method,
@@ -282,18 +287,12 @@ else:
 class Task(Future[_T_co], Generic[_T_co]):  # type: ignore[type-var]  # pyright: ignore[reportGeneralTypeIssues]
     if sys.version_info >= (3, 8):
         def __init__(
-            self,
-            coro: Generator[_TaskYieldType, None, _T_co] | Awaitable[_T_co],
-            *,
-            loop: AbstractEventLoop = ...,
-            name: str | None = ...,
+            self, coro: _TaskCompatibleCoro[_T_co], *, loop: AbstractEventLoop = ..., name: str | None = ...
         ) -> None: ...
     else:
-        def __init__(
-            self, coro: Generator[_TaskYieldType, None, _T_co] | Awaitable[_T_co], *, loop: AbstractEventLoop = ...
-        ) -> None: ...
+        def __init__(self, coro: _TaskCompatibleCoro[_T_co], *, loop: AbstractEventLoop = ...) -> None: ...
     if sys.version_info >= (3, 8):
-        def get_coro(self) -> Generator[_TaskYieldType, None, _T_co] | Awaitable[_T_co]: ...
+        def get_coro(self) -> _TaskCompatibleCoro[_T_co]: ...
         def get_name(self) -> str: ...
         def set_name(self, __value: object) -> None: ...
 
diff --git a/mypy/typeshed/stdlib/binhex.pyi b/mypy/typeshed/stdlib/binhex.pyi
index e0993c840ce7..64ba9f6150b4 100644
--- a/mypy/typeshed/stdlib/binhex.pyi
+++ b/mypy/typeshed/stdlib/binhex.pyi
@@ -1,4 +1,4 @@
-from _typeshed import _BufferWithLen
+from _typeshed import SizedBuffer
 from typing import IO, Any
 from typing_extensions import Literal, TypeAlias
 
@@ -28,9 +28,9 @@ class openrsrc:
 
 class BinHex:
     def __init__(self, name_finfo_dlen_rlen: _FileInfoTuple, ofp: _FileHandleUnion) -> None: ...
-    def write(self, data: _BufferWithLen) -> None: ...
+    def write(self, data: SizedBuffer) -> None: ...
     def close_data(self) -> None: ...
-    def write_rsrc(self, data: _BufferWithLen) -> None: ...
+    def write_rsrc(self, data: SizedBuffer) -> None: ...
     def close(self) -> None: ...
 
 def binhex(inp: str, out: str) -> None: ...
diff --git a/mypy/typeshed/stdlib/builtins.pyi b/mypy/typeshed/stdlib/builtins.pyi
index c72da4aba335..0676aba1277e 100644
--- a/mypy/typeshed/stdlib/builtins.pyi
+++ b/mypy/typeshed/stdlib/builtins.pyi
@@ -36,7 +36,6 @@ from typing import (  # noqa: Y022
     IO,
     Any,
     BinaryIO,
-    ByteString,
     ClassVar,
     Generic,
     Mapping,
@@ -500,7 +499,7 @@ class str(Sequence[str]):
     def __rmul__(self, __value: SupportsIndex) -> str: ...  # type: ignore[misc]
     def __getnewargs__(self) -> tuple[str]: ...
 
-class bytes(ByteString):
+class bytes(Sequence[int]):
     @overload
     def __new__(cls, __o: Iterable[SupportsIndex] | SupportsIndex | SupportsBytes | ReadableBuffer) -> Self: ...
     @overload
@@ -603,7 +602,9 @@ class bytes(ByteString):
     if sys.version_info >= (3, 11):
         def __bytes__(self) -> bytes: ...
 
-class bytearray(MutableSequence[int], ByteString):
+    def __buffer__(self, __flags: int) -> memoryview: ...
+
+class bytearray(MutableSequence[int]):
     @overload
     def __init__(self) -> None: ...
     @overload
@@ -718,6 +719,8 @@ class bytearray(MutableSequence[int], ByteString):
     def __gt__(self, __value: ReadableBuffer) -> bool: ...
     def __ge__(self, __value: ReadableBuffer) -> bool: ...
     def __alloc__(self) -> int: ...
+    def __buffer__(self, __flags: int) -> memoryview: ...
+    def __release_buffer__(self, __buffer: memoryview) -> None: ...
 
 @final
 class memoryview(Sequence[int]):
@@ -779,6 +782,9 @@ class memoryview(Sequence[int]):
     else:
         def hex(self) -> str: ...
 
+    def __buffer__(self, __flags: int) -> memoryview: ...
+    def __release_buffer__(self, __buffer: memoryview) -> None: ...
+
 @final
 class bool(int):
     def __new__(cls, __o: object = ...) -> Self: ...
diff --git a/mypy/typeshed/stdlib/fcntl.pyi b/mypy/typeshed/stdlib/fcntl.pyi
index 90676e365712..01443083f48d 100644
--- a/mypy/typeshed/stdlib/fcntl.pyi
+++ b/mypy/typeshed/stdlib/fcntl.pyi
@@ -1,7 +1,7 @@
 import sys
 from _typeshed import FileDescriptorLike, ReadOnlyBuffer, WriteableBuffer
 from typing import Any, overload
-from typing_extensions import Literal
+from typing_extensions import Buffer, Literal
 
 if sys.platform != "win32":
     FASYNC: int
@@ -104,13 +104,19 @@ if sys.platform != "win32":
     def fcntl(__fd: FileDescriptorLike, __cmd: int, __arg: int = 0) -> int: ...
     @overload
     def fcntl(__fd: FileDescriptorLike, __cmd: int, __arg: str | ReadOnlyBuffer) -> bytes: ...
+    # If arg is an int, return int
     @overload
     def ioctl(__fd: FileDescriptorLike, __request: int, __arg: int = 0, __mutate_flag: bool = True) -> int: ...
+    # The return type works as follows:
+    # - If arg is a read-write buffer, return int if mutate_flag is True, otherwise bytes
+    # - If arg is a read-only buffer, return bytes (and ignore the value of mutate_flag)
+    # We can't represent that precisely as we can't distinguish between read-write and read-only
+    # buffers, so we add overloads for a few unambiguous cases and use Any for the rest.
     @overload
-    def ioctl(__fd: FileDescriptorLike, __request: int, __arg: WriteableBuffer, __mutate_flag: Literal[True] = True) -> int: ...
+    def ioctl(__fd: FileDescriptorLike, __request: int, __arg: bytes, __mutate_flag: bool = True) -> bytes: ...
     @overload
     def ioctl(__fd: FileDescriptorLike, __request: int, __arg: WriteableBuffer, __mutate_flag: Literal[False]) -> bytes: ...
     @overload
-    def ioctl(__fd: FileDescriptorLike, __request: int, __arg: ReadOnlyBuffer, __mutate_flag: bool = True) -> bytes: ...
+    def ioctl(__fd: FileDescriptorLike, __request: int, __arg: Buffer, __mutate_flag: bool = True) -> Any: ...
     def flock(__fd: FileDescriptorLike, __operation: int) -> None: ...
     def lockf(__fd: FileDescriptorLike, __cmd: int, __len: int = 0, __start: int = 0, __whence: int = 0) -> Any: ...
diff --git a/mypy/typeshed/stdlib/fractions.pyi b/mypy/typeshed/stdlib/fractions.pyi
index 3c84978c1bad..7ec8addeb136 100644
--- a/mypy/typeshed/stdlib/fractions.pyi
+++ b/mypy/typeshed/stdlib/fractions.pyi
@@ -22,11 +22,9 @@ else:
 
 class Fraction(Rational):
     @overload
-    def __new__(
-        cls, numerator: int | Rational = 0, denominator: int | Rational | None = None, *, _normalize: bool = True
-    ) -> Self: ...
+    def __new__(cls, numerator: int | Rational = 0, denominator: int | Rational | None = None) -> Self: ...
     @overload
-    def __new__(cls, __value: float | Decimal | str, *, _normalize: bool = True) -> Self: ...
+    def __new__(cls, __value: float | Decimal | str) -> Self: ...
     @classmethod
     def from_float(cls, f: float) -> Self: ...
     @classmethod
@@ -34,6 +32,8 @@ class Fraction(Rational):
     def limit_denominator(self, max_denominator: int = 1000000) -> Fraction: ...
     if sys.version_info >= (3, 8):
         def as_integer_ratio(self) -> tuple[int, int]: ...
+    if sys.version_info >= (3, 12):
+        def is_integer(self) -> bool: ...
 
     @property
     def numerator(a) -> int: ...
diff --git a/mypy/typeshed/stdlib/gzip.pyi b/mypy/typeshed/stdlib/gzip.pyi
index 6a794f381ad6..1ec8b4b8ca7c 100644
--- a/mypy/typeshed/stdlib/gzip.pyi
+++ b/mypy/typeshed/stdlib/gzip.pyi
@@ -1,7 +1,7 @@
 import _compression
 import sys
 import zlib
-from _typeshed import ReadableBuffer, StrOrBytesPath, _BufferWithLen
+from _typeshed import ReadableBuffer, SizedBuffer, StrOrBytesPath
 from io import FileIO
 from typing import Protocol, TextIO, overload
 from typing_extensions import Literal, TypeAlias
@@ -159,9 +159,9 @@ class _GzipReader(_compression.DecompressReader):
     def __init__(self, fp: _ReadableFileobj) -> None: ...
 
 if sys.version_info >= (3, 8):
-    def compress(data: _BufferWithLen, compresslevel: int = 9, *, mtime: float | None = None) -> bytes: ...
+    def compress(data: SizedBuffer, compresslevel: int = 9, *, mtime: float | None = None) -> bytes: ...
 
 else:
-    def compress(data: _BufferWithLen, compresslevel: int = 9) -> bytes: ...
+    def compress(data: SizedBuffer, compresslevel: int = 9) -> bytes: ...
 
 def decompress(data: ReadableBuffer) -> bytes: ...
diff --git a/mypy/typeshed/stdlib/hmac.pyi b/mypy/typeshed/stdlib/hmac.pyi
index ee8af1b48d83..9ff99a5a05d5 100644
--- a/mypy/typeshed/stdlib/hmac.pyi
+++ b/mypy/typeshed/stdlib/hmac.pyi
@@ -1,5 +1,5 @@
 import sys
-from _typeshed import ReadableBuffer, _BufferWithLen
+from _typeshed import ReadableBuffer, SizedBuffer
 from collections.abc import Callable
 from types import ModuleType
 from typing import Any, AnyStr, overload
@@ -46,4 +46,4 @@ class HMAC:
 def compare_digest(__a: ReadableBuffer, __b: ReadableBuffer) -> bool: ...
 @overload
 def compare_digest(__a: AnyStr, __b: AnyStr) -> bool: ...
-def digest(key: _BufferWithLen, msg: ReadableBuffer, digest: _DigestMod) -> bytes: ...
+def digest(key: SizedBuffer, msg: ReadableBuffer, digest: _DigestMod) -> bytes: ...
diff --git a/mypy/typeshed/stdlib/imaplib.pyi b/mypy/typeshed/stdlib/imaplib.pyi
index 1c2112dd37c8..7781559c3888 100644
--- a/mypy/typeshed/stdlib/imaplib.pyi
+++ b/mypy/typeshed/stdlib/imaplib.pyi
@@ -1,7 +1,7 @@
 import subprocess
 import sys
 import time
-from _typeshed import ReadableBuffer, _BufferWithLen
+from _typeshed import ReadableBuffer, SizedBuffer
 from builtins import list as _list  # conflicts with a method named "list"
 from collections.abc import Callable
 from datetime import datetime
@@ -155,7 +155,7 @@ class _Authenticator:
     def __init__(self, mechinst: Callable[[bytes], bytes | bytearray | memoryview | str | None]) -> None: ...
     def process(self, data: str) -> str: ...
     def encode(self, inp: bytes | bytearray | memoryview) -> str: ...
-    def decode(self, inp: str | _BufferWithLen) -> bytes: ...
+    def decode(self, inp: str | SizedBuffer) -> bytes: ...
 
 def Internaldate2tuple(resp: ReadableBuffer) -> time.struct_time | None: ...
 def Int2AP(num: SupportsAbs[SupportsInt]) -> bytes: ...
diff --git a/mypy/typeshed/stdlib/inspect.pyi b/mypy/typeshed/stdlib/inspect.pyi
index a2252e38ee8c..2d004a8e6b57 100644
--- a/mypy/typeshed/stdlib/inspect.pyi
+++ b/mypy/typeshed/stdlib/inspect.pyi
@@ -598,3 +598,25 @@ def classify_class_attrs(cls: type) -> list[Attribute]: ...
 
 if sys.version_info >= (3, 9):
     class ClassFoundException(Exception): ...
+
+if sys.version_info >= (3, 12):
+    class BufferFlags(enum.IntFlag):
+        SIMPLE: int
+        WRITABLE: int
+        FORMAT: int
+        ND: int
+        STRIDES: int
+        C_CONTIGUOUS: int
+        F_CONTIGUOUS: int
+        ANY_CONTIGUOUS: int
+        INDIRECT: int
+        CONTIG: int
+        CONTIG_RO: int
+        STRIDED: int
+        STRIDED_RO: int
+        RECORDS: int
+        RECORDS_RO: int
+        FULL: int
+        FULL_RO: int
+        READ: int
+        WRITE: int
diff --git a/mypy/typeshed/stdlib/json/__init__.pyi b/mypy/typeshed/stdlib/json/__init__.pyi
index 63e9718ee151..dc0cdff926d4 100644
--- a/mypy/typeshed/stdlib/json/__init__.pyi
+++ b/mypy/typeshed/stdlib/json/__init__.pyi
@@ -1,3 +1,4 @@
+import sys
 from _typeshed import SupportsRead, SupportsWrite
 from collections.abc import Callable
 from typing import Any
@@ -6,6 +7,8 @@ from .decoder import JSONDecodeError as JSONDecodeError, JSONDecoder as JSONDeco
 from .encoder import JSONEncoder as JSONEncoder
 
 __all__ = ["dump", "dumps", "load", "loads", "JSONDecoder", "JSONDecodeError", "JSONEncoder"]
+if sys.version_info >= (3, 12):
+    __all__ += ["AttrDict"]
 
 def dumps(
     obj: Any,
@@ -59,3 +62,9 @@ def load(
     **kwds: Any,
 ) -> Any: ...
 def detect_encoding(b: bytes | bytearray) -> str: ...  # undocumented
+
+if sys.version_info >= (3, 12):
+    class AttrDict(dict[str, Any]):
+        def __getattr__(self, name: str) -> Any: ...
+        def __setattr__(self, name: str, value: Any) -> None: ...
+        def __delattr__(self, name: str) -> None: ...
diff --git a/mypy/typeshed/stdlib/logging/handlers.pyi b/mypy/typeshed/stdlib/logging/handlers.pyi
index 3a7c8ade7498..ad5bf392b50f 100644
--- a/mypy/typeshed/stdlib/logging/handlers.pyi
+++ b/mypy/typeshed/stdlib/logging/handlers.pyi
@@ -179,7 +179,7 @@ class SysLogHandler(Handler):
     facility_names: ClassVar[dict[str, int]]  # undocumented
     priority_map: ClassVar[dict[str, str]]  # undocumented
     def __init__(
-        self, address: tuple[str, int] | str = ("localhost", 514), facility: int = 1, socktype: SocketKind | None = None
+        self, address: tuple[str, int] | str = ("localhost", 514), facility: str | int = 1, socktype: SocketKind | None = None
     ) -> None: ...
     if sys.version_info >= (3, 11):
         def createSocket(self) -> None: ...
diff --git a/mypy/typeshed/stdlib/math.pyi b/mypy/typeshed/stdlib/math.pyi
index 231964f397db..4a4d592b860d 100644
--- a/mypy/typeshed/stdlib/math.pyi
+++ b/mypy/typeshed/stdlib/math.pyi
@@ -112,7 +112,10 @@ def log1p(__x: _SupportsFloatOrIndex) -> float: ...
 def log2(__x: _SupportsFloatOrIndex) -> float: ...
 def modf(__x: _SupportsFloatOrIndex) -> tuple[float, float]: ...
 
-if sys.version_info >= (3, 9):
+if sys.version_info >= (3, 12):
+    def nextafter(__x: _SupportsFloatOrIndex, __y: _SupportsFloatOrIndex, *, steps: SupportsIndex | None = None) -> float: ...
+
+elif sys.version_info >= (3, 9):
     def nextafter(__x: _SupportsFloatOrIndex, __y: _SupportsFloatOrIndex) -> float: ...
 
 if sys.version_info >= (3, 8):
@@ -130,6 +133,10 @@ def radians(__x: _SupportsFloatOrIndex) -> float: ...
 def remainder(__x: _SupportsFloatOrIndex, __y: _SupportsFloatOrIndex) -> float: ...
 def sin(__x: _SupportsFloatOrIndex) -> float: ...
 def sinh(__x: _SupportsFloatOrIndex) -> float: ...
+
+if sys.version_info >= (3, 12):
+    def sumprod(__p: Iterable[float], __q: Iterable[float]) -> float: ...
+
 def sqrt(__x: _SupportsFloatOrIndex) -> float: ...
 def tan(__x: _SupportsFloatOrIndex) -> float: ...
 def tanh(__x: _SupportsFloatOrIndex) -> float: ...
diff --git a/mypy/typeshed/stdlib/mmap.pyi b/mypy/typeshed/stdlib/mmap.pyi
index 8da4ea7ca864..38e1924392c4 100644
--- a/mypy/typeshed/stdlib/mmap.pyi
+++ b/mypy/typeshed/stdlib/mmap.pyi
@@ -76,6 +76,8 @@ class mmap(Iterable[int], Sized):
     def __iter__(self) -> Iterator[int]: ...
     def __enter__(self) -> Self: ...
     def __exit__(self, *args: Unused) -> None: ...
+    def __buffer__(self, __flags: int) -> memoryview: ...
+    def __release_buffer__(self, __buffer: memoryview) -> None: ...
 
 if sys.version_info >= (3, 8) and sys.platform != "win32":
     MADV_NORMAL: int
diff --git a/mypy/typeshed/stdlib/pickle.pyi b/mypy/typeshed/stdlib/pickle.pyi
index 55ff38585b95..cf3995d74f5d 100644
--- a/mypy/typeshed/stdlib/pickle.pyi
+++ b/mypy/typeshed/stdlib/pickle.pyi
@@ -103,6 +103,8 @@ if sys.version_info >= (3, 8):
         def __init__(self, buffer: ReadableBuffer) -> None: ...
         def raw(self) -> memoryview: ...
         def release(self) -> None: ...
+        def __buffer__(self, __flags: int) -> memoryview: ...
+        def __release_buffer__(self, __buffer: memoryview) -> None: ...
     _BufferCallback: TypeAlias = Callable[[PickleBuffer], Any] | None
     def dump(
         obj: Any,
diff --git a/mypy/typeshed/stdlib/random.pyi b/mypy/typeshed/stdlib/random.pyi
index 5434f22407cc..9fd1c64f2bba 100644
--- a/mypy/typeshed/stdlib/random.pyi
+++ b/mypy/typeshed/stdlib/random.pyi
@@ -34,6 +34,8 @@ __all__ = [
 
 if sys.version_info >= (3, 9):
     __all__ += ["randbytes"]
+if sys.version_info >= (3, 12):
+    __all__ += ["binomialvariate"]
 
 _T = TypeVar("_T")
 
@@ -79,8 +81,15 @@ class Random(_random.Random):
 
     def uniform(self, a: float, b: float) -> float: ...
     def triangular(self, low: float = 0.0, high: float = 1.0, mode: float | None = None) -> float: ...
+    if sys.version_info >= (3, 12):
+        def binomialvariate(self, n: int = 1, p: float = 0.5) -> int: ...
+
     def betavariate(self, alpha: float, beta: float) -> float: ...
-    def expovariate(self, lambd: float) -> float: ...
+    if sys.version_info >= (3, 12):
+        def expovariate(self, lambd: float = 1.0) -> float: ...
+    else:
+        def expovariate(self, lambd: float) -> float: ...
+
     def gammavariate(self, alpha: float, beta: float) -> float: ...
     if sys.version_info >= (3, 11):
         def gauss(self, mu: float = 0.0, sigma: float = 1.0) -> float: ...
@@ -117,6 +126,8 @@ expovariate = _inst.expovariate
 vonmisesvariate = _inst.vonmisesvariate
 gammavariate = _inst.gammavariate
 gauss = _inst.gauss
+if sys.version_info >= (3, 12):
+    binomialvariate = _inst.binomialvariate
 betavariate = _inst.betavariate
 paretovariate = _inst.paretovariate
 weibullvariate = _inst.weibullvariate
diff --git a/mypy/typeshed/stdlib/shutil.pyi b/mypy/typeshed/stdlib/shutil.pyi
index e8eb468337e1..ef716d4049dd 100644
--- a/mypy/typeshed/stdlib/shutil.pyi
+++ b/mypy/typeshed/stdlib/shutil.pyi
@@ -87,22 +87,46 @@ else:
         ignore_dangling_symlinks: bool = False,
     ) -> _PathReturn: ...
 
-_OnErrorCallback: TypeAlias = Callable[[Callable[..., Any], Any, Any], object]
+_OnErrorCallback: TypeAlias = Callable[[Callable[..., Any], str, Any], object]
+_OnExcCallback: TypeAlias = Callable[[Callable[..., Any], str, Exception], object]
 
 class _RmtreeType(Protocol):
     avoids_symlink_attacks: bool
-    if sys.version_info >= (3, 11):
+    if sys.version_info >= (3, 12):
+        @overload
         def __call__(
             self,
             path: StrOrBytesPath,
-            ignore_errors: bool = ...,
-            onerror: _OnErrorCallback | None = ...,
+            ignore_errors: bool = False,
+            onerror: _OnErrorCallback | None = None,
             *,
-            dir_fd: int | None = ...,
+            onexc: None = None,
+            dir_fd: int | None = None,
+        ) -> None: ...
+        @overload
+        def __call__(
+            self,
+            path: StrOrBytesPath,
+            ignore_errors: bool = False,
+            onerror: None = None,
+            *,
+            onexc: _OnExcCallback,
+            dir_fd: int | None = None,
+        ) -> None: ...
+    elif sys.version_info >= (3, 11):
+        def __call__(
+            self,
+            path: StrOrBytesPath,
+            ignore_errors: bool = False,
+            onerror: _OnErrorCallback | None = None,
+            *,
+            dir_fd: int | None = None,
         ) -> None: ...
 
     else:
-        def __call__(self, path: StrOrBytesPath, ignore_errors: bool = ..., onerror: _OnErrorCallback | None = ...) -> None: ...
+        def __call__(
+            self, path: StrOrBytesPath, ignore_errors: bool = False, onerror: _OnErrorCallback | None = None
+        ) -> None: ...
 
 rmtree: _RmtreeType
 
@@ -167,7 +191,15 @@ def register_archive_format(
     name: str, function: Callable[[str, str], object], extra_args: None = None, description: str = ""
 ) -> None: ...
 def unregister_archive_format(name: str) -> None: ...
-def unpack_archive(filename: StrPath, extract_dir: StrPath | None = None, format: str | None = None) -> None: ...
+
+if sys.version_info >= (3, 12):
+    def unpack_archive(
+        filename: StrPath, extract_dir: StrPath | None = None, format: str | None = None, *, filter: str | None = None
+    ) -> None: ...
+
+else:
+    def unpack_archive(filename: StrPath, extract_dir: StrPath | None = None, format: str | None = None) -> None: ...
+
 @overload
 def register_unpack_format(
     name: str,
diff --git a/mypy/typeshed/stdlib/smtplib.pyi b/mypy/typeshed/stdlib/smtplib.pyi
index 4228ad551eba..584fa164fec9 100644
--- a/mypy/typeshed/stdlib/smtplib.pyi
+++ b/mypy/typeshed/stdlib/smtplib.pyi
@@ -1,6 +1,6 @@
 import sys
 from _socket import _Address as _SourceAddress
-from _typeshed import ReadableBuffer, _BufferWithLen
+from _typeshed import ReadableBuffer, SizedBuffer
 from collections.abc import Sequence
 from email.message import Message as _Message
 from re import Pattern
@@ -133,7 +133,7 @@ class SMTP:
         self,
         from_addr: str,
         to_addrs: str | Sequence[str],
-        msg: _BufferWithLen | str,
+        msg: SizedBuffer | str,
         mail_options: Sequence[str] = (),
         rcpt_options: Sequence[str] = (),
     ) -> _SendErrs: ...
diff --git a/mypy/typeshed/stdlib/statistics.pyi b/mypy/typeshed/stdlib/statistics.pyi
index 1358b1f90d7d..af5fcec6ad0c 100644
--- a/mypy/typeshed/stdlib/statistics.pyi
+++ b/mypy/typeshed/stdlib/statistics.pyi
@@ -114,8 +114,15 @@ if sys.version_info >= (3, 8):
         def __rsub__(self, x2: float | NormalDist) -> NormalDist: ...
         __rmul__ = __mul__
 
-if sys.version_info >= (3, 10):
+if sys.version_info >= (3, 12):
+    def correlation(
+        __x: Sequence[_Number], __y: Sequence[_Number], *, method: Literal["linear", "ranked"] = "linear"
+    ) -> float: ...
+
+elif sys.version_info >= (3, 10):
     def correlation(__x: Sequence[_Number], __y: Sequence[_Number]) -> float: ...
+
+if sys.version_info >= (3, 10):
     def covariance(__x: Sequence[_Number], __y: Sequence[_Number]) -> float: ...
 
     class LinearRegression(NamedTuple):
diff --git a/mypy/typeshed/stdlib/typing.pyi b/mypy/typeshed/stdlib/typing.pyi
index 6fc677dcbdc9..db042dc440ae 100644
--- a/mypy/typeshed/stdlib/typing.pyi
+++ b/mypy/typeshed/stdlib/typing.pyi
@@ -136,14 +136,32 @@ Any = object()
 
 @_final
 class TypeVar:
-    __name__: str
-    __bound__: Any | None
-    __constraints__: tuple[Any, ...]
-    __covariant__: bool
-    __contravariant__: bool
-    def __init__(
-        self, name: str, *constraints: Any, bound: Any | None = None, covariant: bool = False, contravariant: bool = False
-    ) -> None: ...
+    @property
+    def __name__(self) -> str: ...
+    @property
+    def __bound__(self) -> Any | None: ...
+    @property
+    def __constraints__(self) -> tuple[Any, ...]: ...
+    @property
+    def __covariant__(self) -> bool: ...
+    @property
+    def __contravariant__(self) -> bool: ...
+    if sys.version_info >= (3, 12):
+        @property
+        def __infer_variance__(self) -> bool: ...
+        def __init__(
+            self,
+            name: str,
+            *constraints: Any,
+            bound: Any | None = None,
+            covariant: bool = False,
+            contravariant: bool = False,
+            infer_variance: bool = False,
+        ) -> None: ...
+    else:
+        def __init__(
+            self, name: str, *constraints: Any, bound: Any | None = None, covariant: bool = False, contravariant: bool = False
+        ) -> None: ...
     if sys.version_info >= (3, 10):
         def __or__(self, right: Any) -> _SpecialForm: ...
         def __ror__(self, left: Any) -> _SpecialForm: ...
@@ -193,30 +211,55 @@ if sys.version_info >= (3, 11):
     NotRequired: _SpecialForm
     LiteralString: _SpecialForm
 
+    @_final
     class TypeVarTuple:
-        __name__: str
+        @property
+        def __name__(self) -> str: ...
         def __init__(self, name: str) -> None: ...
         def __iter__(self) -> Any: ...
         def __typing_subst__(self, arg: Never) -> Never: ...
         def __typing_prepare_subst__(self, alias: Incomplete, args: Incomplete) -> Incomplete: ...
 
 if sys.version_info >= (3, 10):
+    @_final
     class ParamSpecArgs:
-        __origin__: ParamSpec
+        @property
+        def __origin__(self) -> ParamSpec: ...
         def __init__(self, origin: ParamSpec) -> None: ...
 
+    @_final
     class ParamSpecKwargs:
-        __origin__: ParamSpec
+        @property
+        def __origin__(self) -> ParamSpec: ...
         def __init__(self, origin: ParamSpec) -> None: ...
 
+    @_final
     class ParamSpec:
-        __name__: str
-        __bound__: Any | None
-        __covariant__: bool
-        __contravariant__: bool
-        def __init__(
-            self, name: str, *, bound: Any | None = None, contravariant: bool = False, covariant: bool = False
-        ) -> None: ...
+        @property
+        def __name__(self) -> str: ...
+        @property
+        def __bound__(self) -> Any | None: ...
+        @property
+        def __covariant__(self) -> bool: ...
+        @property
+        def __contravariant__(self) -> bool: ...
+        if sys.version_info >= (3, 12):
+            @property
+            def __infer_variance__(self) -> bool: ...
+            def __init__(
+                self,
+                name: str,
+                *,
+                bound: Any | None = None,
+                contravariant: bool = False,
+                covariant: bool = False,
+                infer_variance: bool = False,
+            ) -> None: ...
+        else:
+            def __init__(
+                self, name: str, *, bound: Any | None = None, contravariant: bool = False, covariant: bool = False
+            ) -> None: ...
+
         @property
         def args(self) -> ParamSpecArgs: ...
         @property
@@ -233,7 +276,7 @@ if sys.version_info >= (3, 10):
 
     class NewType:
         def __init__(self, name: str, tp: Any) -> None: ...
-        def __call__(self, x: _T) -> _T: ...
+        def __call__(self, __x: _T) -> _T: ...
         def __or__(self, other: Any) -> _SpecialForm: ...
         def __ror__(self, other: Any) -> _SpecialForm: ...
         __supertype__: type
@@ -728,7 +771,7 @@ class TextIO(IO[str]):
     @abstractmethod
     def __enter__(self) -> TextIO: ...
 
-class ByteString(Sequence[int], metaclass=ABCMeta): ...
+ByteString: typing_extensions.TypeAlias = bytes | bytearray | memoryview
 
 # Functions
 
@@ -800,18 +843,21 @@ if sys.version_info >= (3, 11):
 
 class NamedTuple(tuple[Any, ...]):
     if sys.version_info < (3, 8):
-        _field_types: collections.OrderedDict[str, type]
+        _field_types: ClassVar[collections.OrderedDict[str, type]]
     elif sys.version_info < (3, 9):
-        _field_types: dict[str, type]
-    _field_defaults: dict[str, Any]
-    _fields: tuple[str, ...]
-    _source: str
+        _field_types: ClassVar[dict[str, type]]
+    _field_defaults: ClassVar[dict[str, Any]]
+    _fields: ClassVar[tuple[str, ...]]
+    # __orig_bases__ sometimes exists on <3.12, but not consistently
+    # So we only add it to the stub on 3.12+.
+    if sys.version_info >= (3, 12):
+        __orig_bases__: ClassVar[tuple[Any, ...]]
     @overload
     def __init__(self, typename: str, fields: Iterable[tuple[str, Any]] = ...) -> None: ...
     @overload
     def __init__(self, typename: str, fields: None = None, **kwargs: Any) -> None: ...
     @classmethod
-    def _make(cls: Type[_T], iterable: Iterable[Any]) -> _T: ...
+    def _make(cls, iterable: Iterable[Any]) -> typing_extensions.Self: ...
     if sys.version_info >= (3, 8):
         def _asdict(self) -> dict[str, Any]: ...
     else:
@@ -827,6 +873,10 @@ class _TypedDict(Mapping[str, object], metaclass=ABCMeta):
     if sys.version_info >= (3, 9):
         __required_keys__: ClassVar[frozenset[str]]
         __optional_keys__: ClassVar[frozenset[str]]
+    # __orig_bases__ sometimes exists on <3.12, but not consistently,
+    # so we only add it to the stub on 3.12+
+    if sys.version_info >= (3, 12):
+        __orig_bases__: ClassVar[tuple[Any, ...]]
     def copy(self) -> typing_extensions.Self: ...
     # Using Never so that only calls using mypy plugin hook that specialize the signature
     # can go through.
@@ -873,3 +923,26 @@ if sys.version_info >= (3, 10):
     def is_typeddict(tp: object) -> bool: ...
 
 def _type_repr(obj: object) -> str: ...
+
+if sys.version_info >= (3, 12):
+    def override(__arg: _F) -> _F: ...
+    @_final
+    class TypeAliasType:
+        def __init__(
+            self, name: str, value: Any, *, type_params: tuple[TypeVar | ParamSpec | TypeVarTuple, ...] = ()
+        ) -> None: ...
+        @property
+        def __value__(self) -> Any: ...
+        @property
+        def __type_params__(self) -> tuple[TypeVar | ParamSpec | TypeVarTuple, ...]: ...
+        @property
+        def __parameters__(self) -> tuple[Any, ...]: ...
+        @property
+        def __name__(self) -> str: ...
+        # It's writable on types, but not on instances of TypeAliasType.
+        @property
+        def __module__(self) -> str | None: ...  # type: ignore[override]
+        def __getitem__(self, parameters: Any) -> Any: ...
+        if sys.version_info >= (3, 10):
+            def __or__(self, right: Any) -> _SpecialForm: ...
+            def __ror__(self, left: Any) -> _SpecialForm: ...
diff --git a/mypy/typeshed/stdlib/typing_extensions.pyi b/mypy/typeshed/stdlib/typing_extensions.pyi
index d567d8b96faf..93087a45a108 100644
--- a/mypy/typeshed/stdlib/typing_extensions.pyi
+++ b/mypy/typeshed/stdlib/typing_extensions.pyi
@@ -22,9 +22,14 @@ from typing import (  # noqa: Y022,Y039
     DefaultDict as DefaultDict,
     Deque as Deque,
     Mapping,
-    NewType as NewType,
     NoReturn as NoReturn,
     Sequence,
+    SupportsAbs as SupportsAbs,
+    SupportsBytes as SupportsBytes,
+    SupportsComplex as SupportsComplex,
+    SupportsFloat as SupportsFloat,
+    SupportsInt as SupportsInt,
+    SupportsRound as SupportsRound,
     Text as Text,
     Type as Type,
     _Alias,
@@ -39,6 +44,7 @@ if sys.version_info >= (3, 9):
 
 __all__ = [
     "Any",
+    "Buffer",
     "ClassVar",
     "Concatenate",
     "Final",
@@ -66,6 +72,12 @@ __all__ = [
     "OrderedDict",
     "TypedDict",
     "SupportsIndex",
+    "SupportsAbs",
+    "SupportsRound",
+    "SupportsBytes",
+    "SupportsComplex",
+    "SupportsFloat",
+    "SupportsInt",
     "Annotated",
     "assert_never",
     "assert_type",
@@ -84,6 +96,7 @@ __all__ = [
     "runtime_checkable",
     "Text",
     "TypeAlias",
+    "TypeAliasType",
     "TypeGuard",
     "TYPE_CHECKING",
     "Never",
@@ -93,6 +106,7 @@ __all__ = [
     "clear_overloads",
     "get_args",
     "get_origin",
+    "get_original_bases",
     "get_overloads",
     "get_type_hints",
 ]
@@ -134,6 +148,7 @@ class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
     __required_keys__: ClassVar[frozenset[str]]
     __optional_keys__: ClassVar[frozenset[str]]
     __total__: ClassVar[bool]
+    __orig_bases__: ClassVar[tuple[Any, ...]]
     def copy(self) -> Self: ...
     # Using Never so that only calls using mypy plugin hook that specialize the signature
     # can go through.
@@ -183,10 +198,11 @@ class SupportsIndex(Protocol, metaclass=abc.ABCMeta):
     @abc.abstractmethod
     def __index__(self) -> int: ...
 
-# New things in 3.10
+# New and changed things in 3.10
 if sys.version_info >= (3, 10):
     from typing import (
         Concatenate as Concatenate,
+        NewType as NewType,
         ParamSpecArgs as ParamSpecArgs,
         ParamSpecKwargs as ParamSpecKwargs,
         TypeAlias as TypeAlias,
@@ -194,12 +210,16 @@ if sys.version_info >= (3, 10):
         is_typeddict as is_typeddict,
     )
 else:
+    @final
     class ParamSpecArgs:
-        __origin__: ParamSpec
+        @property
+        def __origin__(self) -> ParamSpec: ...
         def __init__(self, origin: ParamSpec) -> None: ...
 
+    @final
     class ParamSpecKwargs:
-        __origin__: ParamSpec
+        @property
+        def __origin__(self) -> ParamSpec: ...
         def __init__(self, origin: ParamSpec) -> None: ...
 
     Concatenate: _SpecialForm
@@ -207,6 +227,11 @@ else:
     TypeGuard: _SpecialForm
     def is_typeddict(tp: object) -> bool: ...
 
+    class NewType:
+        def __init__(self, name: str, tp: Any) -> None: ...
+        def __call__(self, __x: _T) -> _T: ...
+        __supertype__: type
+
 # New things in 3.11
 # NamedTuples are not new, but the ability to create generic NamedTuples is new in 3.11
 if sys.version_info >= (3, 11):
@@ -251,12 +276,12 @@ else:
 
     class NamedTuple(tuple[Any, ...]):
         if sys.version_info < (3, 8):
-            _field_types: collections.OrderedDict[str, type]
+            _field_types: ClassVar[collections.OrderedDict[str, type]]
         elif sys.version_info < (3, 9):
-            _field_types: dict[str, type]
-        _field_defaults: dict[str, Any]
-        _fields: tuple[str, ...]
-        _source: str
+            _field_types: ClassVar[dict[str, type]]
+        _field_defaults: ClassVar[dict[str, Any]]
+        _fields: ClassVar[tuple[str, ...]]
+        __orig_bases__: ClassVar[tuple[Any, ...]]
         @overload
         def __init__(self, typename: str, fields: Iterable[tuple[str, Any]] = ...) -> None: ...
         @overload
@@ -272,16 +297,24 @@ else:
 
 # New things in 3.xx
 # The `default` parameter was added to TypeVar, ParamSpec, and TypeVarTuple (PEP 696)
-# The `infer_variance` parameter was added to TypeVar (PEP 695)
+# The `infer_variance` parameter was added to TypeVar in 3.12 (PEP 695)
 # typing_extensions.override (PEP 698)
 @final
 class TypeVar:
-    __name__: str
-    __bound__: Any | None
-    __constraints__: tuple[Any, ...]
-    __covariant__: bool
-    __contravariant__: bool
-    __default__: Any | None
+    @property
+    def __name__(self) -> str: ...
+    @property
+    def __bound__(self) -> Any | None: ...
+    @property
+    def __constraints__(self) -> tuple[Any, ...]: ...
+    @property
+    def __covariant__(self) -> bool: ...
+    @property
+    def __contravariant__(self) -> bool: ...
+    @property
+    def __infer_variance__(self) -> bool: ...
+    @property
+    def __default__(self) -> Any | None: ...
     def __init__(
         self,
         name: str,
@@ -300,11 +333,18 @@ class TypeVar:
 
 @final
 class ParamSpec:
-    __name__: str
-    __bound__: type[Any] | None
-    __covariant__: bool
-    __contravariant__: bool
-    __default__: type[Any] | None
+    @property
+    def __name__(self) -> str: ...
+    @property
+    def __bound__(self) -> Any | None: ...
+    @property
+    def __covariant__(self) -> bool: ...
+    @property
+    def __contravariant__(self) -> bool: ...
+    @property
+    def __infer_variance__(self) -> bool: ...
+    @property
+    def __default__(self) -> Any | None: ...
     def __init__(
         self,
         name: str,
@@ -321,10 +361,45 @@ class ParamSpec:
 
 @final
 class TypeVarTuple:
-    __name__: str
-    __default__: Any | None
+    @property
+    def __name__(self) -> str: ...
+    @property
+    def __default__(self) -> Any | None: ...
     def __init__(self, name: str, *, default: Any | None = None) -> None: ...
     def __iter__(self) -> Any: ...  # Unpack[Self]
 
-def override(__arg: _F) -> _F: ...
 def deprecated(__msg: str, *, category: type[Warning] | None = ..., stacklevel: int = 1) -> Callable[[_T], _T]: ...
+
+if sys.version_info >= (3, 12):
+    from collections.abc import Buffer as Buffer
+    from types import get_original_bases as get_original_bases
+    from typing import TypeAliasType as TypeAliasType, override as override
+else:
+    def override(__arg: _F) -> _F: ...
+    def get_original_bases(__cls: type) -> tuple[Any, ...]: ...
+    @final
+    class TypeAliasType:
+        def __init__(
+            self, name: str, value: Any, *, type_params: tuple[TypeVar | ParamSpec | TypeVarTuple, ...] = ()
+        ) -> None: ...
+        @property
+        def __value__(self) -> Any: ...
+        @property
+        def __type_params__(self) -> tuple[TypeVar | ParamSpec | TypeVarTuple, ...]: ...
+        @property
+        def __parameters__(self) -> tuple[Any, ...]: ...
+        @property
+        def __name__(self) -> str: ...
+        # It's writable on types, but not on instances of TypeAliasType.
+        @property
+        def __module__(self) -> str | None: ...  # type: ignore[override]
+        def __getitem__(self, parameters: Any) -> Any: ...
+        if sys.version_info >= (3, 10):
+            def __or__(self, right: Any) -> _SpecialForm: ...
+            def __ror__(self, left: Any) -> _SpecialForm: ...
+
+    @runtime_checkable
+    class Buffer(Protocol):
+        # Not actually a Protocol at runtime; see
+        # https://github.com/python/typeshed/issues/10224 for why we're defining it this way
+        def __buffer__(self, __flags: int) -> memoryview: ...
diff --git a/mypy/typeshed/stdlib/weakref.pyi b/mypy/typeshed/stdlib/weakref.pyi
index 0bbab52f9b08..13f48fe85a8d 100644
--- a/mypy/typeshed/stdlib/weakref.pyi
+++ b/mypy/typeshed/stdlib/weakref.pyi
@@ -41,7 +41,7 @@ _P = ParamSpec("_P")
 ProxyTypes: tuple[type[Any], ...]
 
 class WeakMethod(ref[_CallableT], Generic[_CallableT]):
-    def __new__(cls, meth: _CallableT, callback: Callable[[_CallableT], object] | None = None) -> Self: ...
+    def __new__(cls, meth: _CallableT, callback: Callable[[Self], object] | None = None) -> Self: ...
     def __call__(self) -> _CallableT | None: ...
     def __eq__(self, other: object) -> bool: ...
     def __ne__(self, other: object) -> bool: ...
diff --git a/mypy/typeshed/stdlib/xmlrpc/client.pyi b/mypy/typeshed/stdlib/xmlrpc/client.pyi
index 8c32f3080749..79969359f091 100644
--- a/mypy/typeshed/stdlib/xmlrpc/client.pyi
+++ b/mypy/typeshed/stdlib/xmlrpc/client.pyi
@@ -2,7 +2,7 @@ import gzip
 import http.client
 import sys
 import time
-from _typeshed import ReadableBuffer, SupportsRead, SupportsWrite, _BufferWithLen
+from _typeshed import ReadableBuffer, SizedBuffer, SupportsRead, SupportsWrite
 from collections.abc import Callable, Iterable, Mapping
 from datetime import datetime
 from io import BytesIO
@@ -236,20 +236,20 @@ class Transport:
         def __init__(self, use_datetime: bool = False, use_builtin_types: bool = False) -> None: ...
 
     def request(
-        self, host: _HostType, handler: str, request_body: _BufferWithLen, verbose: bool = False
+        self, host: _HostType, handler: str, request_body: SizedBuffer, verbose: bool = False
     ) -> tuple[_Marshallable, ...]: ...
     def single_request(
-        self, host: _HostType, handler: str, request_body: _BufferWithLen, verbose: bool = False
+        self, host: _HostType, handler: str, request_body: SizedBuffer, verbose: bool = False
     ) -> tuple[_Marshallable, ...]: ...
     def getparser(self) -> tuple[ExpatParser, Unmarshaller]: ...
     def get_host_info(self, host: _HostType) -> tuple[str, list[tuple[str, str]], dict[str, str]]: ...
     def make_connection(self, host: _HostType) -> http.client.HTTPConnection: ...
     def close(self) -> None: ...
     def send_request(
-        self, host: _HostType, handler: str, request_body: _BufferWithLen, debug: bool
+        self, host: _HostType, handler: str, request_body: SizedBuffer, debug: bool
     ) -> http.client.HTTPConnection: ...
     def send_headers(self, connection: http.client.HTTPConnection, headers: list[tuple[str, str]]) -> None: ...
-    def send_content(self, connection: http.client.HTTPConnection, request_body: _BufferWithLen) -> None: ...
+    def send_content(self, connection: http.client.HTTPConnection, request_body: SizedBuffer) -> None: ...
     def parse_response(self, response: http.client.HTTPResponse) -> tuple[_Marshallable, ...]: ...
 
 class SafeTransport(Transport):
diff --git a/mypy/typeshed/stdlib/zipfile.pyi b/mypy/typeshed/stdlib/zipfile.pyi
index 92f1dc49adbc..abda7a3b9625 100644
--- a/mypy/typeshed/stdlib/zipfile.pyi
+++ b/mypy/typeshed/stdlib/zipfile.pyi
@@ -1,6 +1,6 @@
 import io
 import sys
-from _typeshed import StrOrBytesPath, StrPath, _BufferWithLen
+from _typeshed import SizedBuffer, StrOrBytesPath, StrPath
 from collections.abc import Callable, Iterable, Iterator
 from os import PathLike
 from types import TracebackType
@@ -179,7 +179,7 @@ class ZipFile:
     def writestr(
         self,
         zinfo_or_arcname: str | ZipInfo,
-        data: _BufferWithLen | str,
+        data: SizedBuffer | str,
         compress_type: int | None = None,
         compresslevel: int | None = None,
     ) -> None: ...
diff --git a/test-data/unit/pythoneval.test b/test-data/unit/pythoneval.test
index 760a761705f4..7108734102d1 100644
--- a/test-data/unit/pythoneval.test
+++ b/test-data/unit/pythoneval.test
@@ -1019,7 +1019,7 @@ re.subn(bpat, lambda m: b'', b'')[0] + b''
 _testReModuleBytes.py:7: error: No overload variant of "search" matches argument types "bytes", "str"
 _testReModuleBytes.py:7: note: Possible overload variants:
 _testReModuleBytes.py:7: note:     def search(pattern: Union[str, Pattern[str]], string: str, flags: Union[int, RegexFlag] = ...) -> Optional[Match[str]]
-_testReModuleBytes.py:7: note:     def search(pattern: Union[bytes, Pattern[bytes]], string: Union[bytes, Union[bytearray, memoryview, array[Any], mmap, _CData]], flags: Union[int, RegexFlag] = ...) -> Optional[Match[bytes]]
+_testReModuleBytes.py:7: note:     def search(pattern: Union[bytes, Pattern[bytes]], string: Buffer, flags: Union[int, RegexFlag] = ...) -> Optional[Match[bytes]]
 _testReModuleBytes.py:9: error: Argument 1 to "search" has incompatible type "Pattern[bytes]"; expected "Union[str, Pattern[str]]"
 
 [case testReModuleString]
@@ -1046,7 +1046,7 @@ re.subn(spat, lambda m: '', '')[0] + ''
 _testReModuleString.py:7: error: No overload variant of "search" matches argument types "str", "bytes"
 _testReModuleString.py:7: note: Possible overload variants:
 _testReModuleString.py:7: note:     def search(pattern: Union[str, Pattern[str]], string: str, flags: Union[int, RegexFlag] = ...) -> Optional[Match[str]]
-_testReModuleString.py:7: note:     def search(pattern: Union[bytes, Pattern[bytes]], string: Union[bytes, Union[bytearray, memoryview, array[Any], mmap, _CData]], flags: Union[int, RegexFlag] = ...) -> Optional[Match[bytes]]
+_testReModuleString.py:7: note:     def search(pattern: Union[bytes, Pattern[bytes]], string: Buffer, flags: Union[int, RegexFlag] = ...) -> Optional[Match[bytes]]
 _testReModuleString.py:9: error: Argument 1 to "search" has incompatible type "Pattern[str]"; expected "Union[bytes, Pattern[bytes]]"
 
 [case testListSetitemTuple]