diff --git a/pandas/_libs/tslibs/timestamps.pyi b/pandas/_libs/tslibs/timestamps.pyi
index 9693f18e2e05d..ecddd83322bbf 100644
--- a/pandas/_libs/tslibs/timestamps.pyi
+++ b/pandas/_libs/tslibs/timestamps.pyi
@@ -21,7 +21,7 @@ from pandas._libs.tslibs import (
     Timedelta,
 )
 
-_S = TypeVar("_S", bound=datetime)
+_DatetimeT = TypeVar("_DatetimeT", bound=datetime)
 
 def integer_op_not_supported(obj: object) -> TypeError: ...
 
@@ -34,7 +34,7 @@ class Timestamp(datetime):
 
     # error: "__new__" must return a class instance (got "Union[Timestamp, NaTType]")
     def __new__(  # type: ignore[misc]
-        cls: type[_S],
+        cls: type[_DatetimeT],
         ts_input: int
         | np.integer
         | float
@@ -56,7 +56,7 @@ class Timestamp(datetime):
         tzinfo: _tzinfo | None = ...,
         *,
         fold: int | None = ...,
-    ) -> _S | NaTType: ...
+    ) -> _DatetimeT | NaTType: ...
     def _set_freq(self, freq: BaseOffset | None) -> None: ...
     @property
     def year(self) -> int: ...
@@ -79,27 +79,29 @@ class Timestamp(datetime):
     @property
     def fold(self) -> int: ...
     @classmethod
-    def fromtimestamp(cls: type[_S], t: float, tz: _tzinfo | None = ...) -> _S: ...
+    def fromtimestamp(
+        cls: type[_DatetimeT], t: float, tz: _tzinfo | None = ...
+    ) -> _DatetimeT: ...
     @classmethod
-    def utcfromtimestamp(cls: type[_S], t: float) -> _S: ...
+    def utcfromtimestamp(cls: type[_DatetimeT], t: float) -> _DatetimeT: ...
     @classmethod
-    def today(cls: type[_S], tz: _tzinfo | str | None = ...) -> _S: ...
+    def today(cls: type[_DatetimeT], tz: _tzinfo | str | None = ...) -> _DatetimeT: ...
     @classmethod
     def fromordinal(
-        cls: type[_S],
+        cls: type[_DatetimeT],
         ordinal: int,
         freq: str | BaseOffset | None = ...,
         tz: _tzinfo | str | None = ...,
-    ) -> _S: ...
+    ) -> _DatetimeT: ...
     @classmethod
-    def now(cls: type[_S], tz: _tzinfo | str | None = ...) -> _S: ...
+    def now(cls: type[_DatetimeT], tz: _tzinfo | str | None = ...) -> _DatetimeT: ...
     @classmethod
-    def utcnow(cls: type[_S]) -> _S: ...
+    def utcnow(cls: type[_DatetimeT]) -> _DatetimeT: ...
     # error: Signature of "combine" incompatible with supertype "datetime"
     @classmethod
     def combine(cls, date: _date, time: _time) -> datetime: ...  # type: ignore[override]
     @classmethod
-    def fromisoformat(cls: type[_S], date_string: str) -> _S: ...
+    def fromisoformat(cls: type[_DatetimeT], date_string: str) -> _DatetimeT: ...
     def strftime(self, format: str) -> str: ...
     def __format__(self, fmt: str) -> str: ...
     def toordinal(self) -> int: ...
@@ -121,10 +123,9 @@ class Timestamp(datetime):
         tzinfo: _tzinfo | None = ...,
         fold: int = ...,
     ) -> datetime: ...
-    def astimezone(self: _S, tz: _tzinfo | None = ...) -> _S: ...
+    def astimezone(self: _DatetimeT, tz: _tzinfo | None = ...) -> _DatetimeT: ...
     def ctime(self) -> str: ...
-    # error: Signature of "isoformat" incompatible with supertype "datetime"
-    def isoformat(self, sep: str = ...) -> str: ...  # type: ignore[override]
+    def isoformat(self, sep: str = ..., timespec: str = ...) -> str: ...
     @classmethod
     def strptime(cls, date_string: str, format: str) -> datetime: ...
     def utcoffset(self) -> timedelta | None: ...
@@ -139,8 +140,8 @@ class Timestamp(datetime):
     def __add__(self, other: np.ndarray) -> np.ndarray: ...
     @overload
     # TODO: other can also be Tick (but it cannot be resolved)
-    def __add__(self: _S, other: timedelta | np.timedelta64) -> _S: ...
-    def __radd__(self: _S, other: timedelta) -> _S: ...
+    def __add__(self: _DatetimeT, other: timedelta | np.timedelta64) -> _DatetimeT: ...
+    def __radd__(self: _DatetimeT, other: timedelta) -> _DatetimeT: ...
     @overload  # type: ignore
     def __sub__(self, other: datetime) -> timedelta: ...
     @overload
@@ -170,22 +171,25 @@ class Timestamp(datetime):
     def to_julian_date(self) -> np.float64: ...
     @property
     def asm8(self) -> np.datetime64: ...
-    def tz_convert(self: _S, tz: _tzinfo | str | None) -> _S: ...
+    def tz_convert(self: _DatetimeT, tz: _tzinfo | str | None) -> _DatetimeT: ...
     # TODO: could return NaT?
     def tz_localize(
-        self: _S, tz: _tzinfo | str | None, ambiguous: str = ..., nonexistent: str = ...
-    ) -> _S: ...
-    def normalize(self: _S) -> _S: ...
+        self: _DatetimeT,
+        tz: _tzinfo | str | None,
+        ambiguous: str = ...,
+        nonexistent: str = ...,
+    ) -> _DatetimeT: ...
+    def normalize(self: _DatetimeT) -> _DatetimeT: ...
     # TODO: round/floor/ceil could return NaT?
     def round(
-        self: _S, freq: str, ambiguous: bool | str = ..., nonexistent: str = ...
-    ) -> _S: ...
+        self: _DatetimeT, freq: str, ambiguous: bool | str = ..., nonexistent: str = ...
+    ) -> _DatetimeT: ...
     def floor(
-        self: _S, freq: str, ambiguous: bool | str = ..., nonexistent: str = ...
-    ) -> _S: ...
+        self: _DatetimeT, freq: str, ambiguous: bool | str = ..., nonexistent: str = ...
+    ) -> _DatetimeT: ...
     def ceil(
-        self: _S, freq: str, ambiguous: bool | str = ..., nonexistent: str = ...
-    ) -> _S: ...
+        self: _DatetimeT, freq: str, ambiguous: bool | str = ..., nonexistent: str = ...
+    ) -> _DatetimeT: ...
     def day_name(self, locale: str | None = ...) -> str: ...
     def month_name(self, locale: str | None = ...) -> str: ...
     @property