diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 0116207675889..03e86758b64ed 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -4121,7 +4121,6 @@ def add_suffix(self: FrameOrSeries, suffix: str) -> FrameOrSeries:
 
     def sort_values(
         self,
-        by=None,
         axis=0,
         ascending=True,
         inplace: bool_t = False,
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 3e1f011fde51a..ed338700f1011 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -4,7 +4,18 @@
 from io import StringIO
 from shutil import get_terminal_size
 from textwrap import dedent
-from typing import IO, Any, Callable, Hashable, List, Optional
+from typing import (
+    IO,
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Hashable,
+    Iterable,
+    List,
+    Optional,
+    Tuple,
+    Type,
+)
 import warnings
 
 import numpy as np
@@ -12,6 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
+from pandas._typing import Label
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -80,6 +92,9 @@
 import pandas.io.formats.format as fmt
 import pandas.plotting
 
+if TYPE_CHECKING:
+    from pandas.core.frame import DataFrame
+
 __all__ = ["Series"]
 
 _shared_doc_kwargs = dict(
@@ -356,11 +371,11 @@ def _init_dict(self, data, index=None, dtype=None):
     # ----------------------------------------------------------------------
 
     @property
-    def _constructor(self):
+    def _constructor(self) -> Type["Series"]:
         return Series
 
     @property
-    def _constructor_expanddim(self):
+    def _constructor_expanddim(self) -> Type["DataFrame"]:
         from pandas.core.frame import DataFrame
 
         return DataFrame
@@ -372,7 +387,7 @@ def _can_hold_na(self):
 
     _index = None
 
-    def _set_axis(self, axis, labels, fastpath=False):
+    def _set_axis(self, axis, labels, fastpath=False) -> None:
         """
         Override generic, we want to set the _typ here.
         """
@@ -517,7 +532,7 @@ def __len__(self) -> int:
         """
         return len(self._data)
 
-    def view(self, dtype=None):
+    def view(self, dtype=None) -> "Series":
         """
         Create a new view of the Series.
 
@@ -729,7 +744,7 @@ def __array__(self, dtype=None) -> np.ndarray:
 
     # ----------------------------------------------------------------------
 
-    def _unpickle_series_compat(self, state):
+    def _unpickle_series_compat(self, state) -> None:
         if isinstance(state, dict):
             self._data = state["_data"]
             self.name = state["name"]
@@ -760,7 +775,7 @@ def _unpickle_series_compat(self, state):
 
     # indexers
     @property
-    def axes(self):
+    def axes(self) -> List[Index]:
         """
         Return a list of the row axis labels.
         """
@@ -770,7 +785,7 @@ def axes(self):
     # Indexing Methods
 
     @Appender(generic.NDFrame.take.__doc__)
-    def take(self, indices, axis=0, is_copy=False, **kwargs):
+    def take(self, indices, axis=0, is_copy=False, **kwargs) -> "Series":
         nv.validate_take(tuple(), kwargs)
 
         indices = ensure_platform_int(indices)
@@ -816,7 +831,7 @@ def _ixs(self, i: int, axis: int = 0):
         else:
             return values[i]
 
-    def _slice(self, slobj: slice, axis: int = 0, kind=None):
+    def _slice(self, slobj: slice, axis: int = 0, kind=None) -> "Series":
         slobj = self.index._convert_slice_indexer(slobj, kind=kind or "getitem")
         return self._get_values(slobj)
 
@@ -1100,7 +1115,7 @@ def _set_value(self, label, value, takeable: bool = False):
     def _is_mixed_type(self):
         return False
 
-    def repeat(self, repeats, axis=None):
+    def repeat(self, repeats, axis=None) -> "Series":
         """
         Repeat elements of a Series.
 
@@ -1425,7 +1440,7 @@ def to_markdown(
 
     # ----------------------------------------------------------------------
 
-    def items(self):
+    def items(self) -> Iterable[Tuple[Label, Any]]:
         """
         Lazily iterate over (index, value) tuples.
 
@@ -1455,13 +1470,13 @@ def items(self):
         return zip(iter(self.index), iter(self))
 
     @Appender(items.__doc__)
-    def iteritems(self):
+    def iteritems(self) -> Iterable[Tuple[Label, Any]]:
         return self.items()
 
     # ----------------------------------------------------------------------
     # Misc public methods
 
-    def keys(self):
+    def keys(self) -> Index:
         """
         Return alias for index.
 
@@ -1507,7 +1522,7 @@ def to_dict(self, into=dict):
         into_c = com.standardize_mapping(into)
         return into_c(self.items())
 
-    def to_frame(self, name=None):
+    def to_frame(self, name=None) -> "DataFrame":
         """
         Convert Series to DataFrame.
 
@@ -1539,7 +1554,7 @@ def to_frame(self, name=None):
 
         return df
 
-    def _set_name(self, name, inplace=False):
+    def _set_name(self, name, inplace=False) -> "Series":
         """
         Set the Series name.
 
@@ -1681,7 +1696,7 @@ def count(self, level=None):
         out = np.bincount(obs, minlength=len(lev) or None)
         return self._constructor(out, index=lev, dtype="int64").__finalize__(self)
 
-    def mode(self, dropna=True):
+    def mode(self, dropna=True) -> "Series":
         """
         Return the mode(s) of the dataset.
 
@@ -1766,7 +1781,7 @@ def unique(self):
         result = super().unique()
         return result
 
-    def drop_duplicates(self, keep="first", inplace=False):
+    def drop_duplicates(self, keep="first", inplace=False) -> "Series":
         """
         Return Series with duplicate values removed.
 
@@ -1843,7 +1858,7 @@ def drop_duplicates(self, keep="first", inplace=False):
         """
         return super().drop_duplicates(keep=keep, inplace=inplace)
 
-    def duplicated(self, keep="first"):
+    def duplicated(self, keep="first") -> "Series":
         """
         Indicate duplicate Series values.
 
@@ -2062,7 +2077,7 @@ def idxmax(self, axis=0, skipna=True, *args, **kwargs):
             return np.nan
         return self.index[i]
 
-    def round(self, decimals=0, *args, **kwargs):
+    def round(self, decimals=0, *args, **kwargs) -> "Series":
         """
         Round each value in a Series to the given number of decimals.
 
@@ -2157,7 +2172,7 @@ def quantile(self, q=0.5, interpolation="linear"):
             # scalar
             return result.iloc[0]
 
-    def corr(self, other, method="pearson", min_periods=None):
+    def corr(self, other, method="pearson", min_periods=None) -> float:
         """
         Compute correlation with `other` Series, excluding missing values.
 
@@ -2210,7 +2225,7 @@ def corr(self, other, method="pearson", min_periods=None):
             f"'{method}' was supplied"
         )
 
-    def cov(self, other, min_periods=None):
+    def cov(self, other, min_periods=None) -> float:
         """
         Compute covariance with Series, excluding missing values.
 
@@ -2239,7 +2254,7 @@ def cov(self, other, min_periods=None):
             return np.nan
         return nanops.nancov(this.values, other.values, min_periods=min_periods)
 
-    def diff(self, periods=1):
+    def diff(self, periods=1) -> "Series":
         """
         First discrete difference of element.
 
@@ -2303,7 +2318,7 @@ def diff(self, periods=1):
         result = algorithms.diff(com.values_from_object(self), periods)
         return self._constructor(result, index=self.index).__finalize__(self)
 
-    def autocorr(self, lag=1):
+    def autocorr(self, lag=1) -> float:
         """
         Compute the lag-N autocorrelation.
 
@@ -2446,7 +2461,7 @@ def searchsorted(self, value, side="left", sorter=None):
     # -------------------------------------------------------------------
     # Combination
 
-    def append(self, to_append, ignore_index=False, verify_integrity=False):
+    def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Series":
         """
         Concatenate two or more Series.
 
@@ -2523,8 +2538,10 @@ def append(self, to_append, ignore_index=False, verify_integrity=False):
             to_concat.extend(to_append)
         else:
             to_concat = [self, to_append]
-        return concat(
-            to_concat, ignore_index=ignore_index, verify_integrity=verify_integrity
+        return self._ensure_type(
+            concat(
+                to_concat, ignore_index=ignore_index, verify_integrity=verify_integrity
+            )
         )
 
     def _binop(self, other, func, level=None, fill_value=None):
@@ -2566,7 +2583,7 @@ def _binop(self, other, func, level=None, fill_value=None):
         ret = ops._construct_result(self, result, new_index, name)
         return ret
 
-    def combine(self, other, func, fill_value=None):
+    def combine(self, other, func, fill_value=None) -> "Series":
         """
         Combine the Series with a Series or scalar according to `func`.
 
@@ -2663,7 +2680,7 @@ def combine(self, other, func, fill_value=None):
             new_values = try_cast_to_ea(self._values, new_values)
         return self._constructor(new_values, index=new_index, name=new_name)
 
-    def combine_first(self, other):
+    def combine_first(self, other) -> "Series":
         """
         Combine Series values, choosing the calling Series's values first.
 
@@ -2703,7 +2720,7 @@ def combine_first(self, other):
 
         return this.where(notna(this), other)
 
-    def update(self, other):
+    def update(self, other) -> None:
         """
         Modify Series in place using non-NA values from passed
         Series. Aligns on index.
@@ -2762,10 +2779,10 @@ def sort_values(
         self,
         axis=0,
         ascending=True,
-        inplace=False,
-        kind="quicksort",
-        na_position="last",
-        ignore_index=False,
+        inplace: bool = False,
+        kind: str = "quicksort",
+        na_position: str = "last",
+        ignore_index: bool = False,
     ):
         """
         Sort by the values.
@@ -3117,7 +3134,7 @@ def sort_index(
         else:
             return result.__finalize__(self)
 
-    def argsort(self, axis=0, kind="quicksort", order=None):
+    def argsort(self, axis=0, kind="quicksort", order=None) -> "Series":
         """
         Override ndarray.argsort. Argsorts the value, omitting NA/null values,
         and places the result in the same locations as the non-NA values.
@@ -3155,7 +3172,7 @@ def argsort(self, axis=0, kind="quicksort", order=None):
                 np.argsort(values, kind=kind), index=self.index, dtype="int64"
             ).__finalize__(self)
 
-    def nlargest(self, n=5, keep="first"):
+    def nlargest(self, n=5, keep="first") -> "Series":
         """
         Return the largest `n` elements.
 
@@ -3253,7 +3270,7 @@ def nlargest(self, n=5, keep="first"):
         """
         return algorithms.SelectNSeries(self, n=n, keep=keep).nlargest()
 
-    def nsmallest(self, n=5, keep="first"):
+    def nsmallest(self, n=5, keep="first") -> "Series":
         """
         Return the smallest `n` elements.
 
@@ -3350,7 +3367,7 @@ def nsmallest(self, n=5, keep="first"):
         """
         return algorithms.SelectNSeries(self, n=n, keep=keep).nsmallest()
 
-    def swaplevel(self, i=-2, j=-1, copy=True):
+    def swaplevel(self, i=-2, j=-1, copy=True) -> "Series":
         """
         Swap levels i and j in a :class:`MultiIndex`.
 
@@ -3373,7 +3390,7 @@ def swaplevel(self, i=-2, j=-1, copy=True):
             self
         )
 
-    def reorder_levels(self, order):
+    def reorder_levels(self, order) -> "Series":
         """
         Rearrange index levels using input order.
 
@@ -3497,7 +3514,7 @@ def unstack(self, level=-1, fill_value=None):
     # ----------------------------------------------------------------------
     # function application
 
-    def map(self, arg, na_action=None):
+    def map(self, arg, na_action=None) -> "Series":
         """
         Map values of Series according to input correspondence.
 
@@ -3575,7 +3592,7 @@ def map(self, arg, na_action=None):
         new_values = super()._map_values(arg, na_action=na_action)
         return self._constructor(new_values, index=self.index).__finalize__(self)
 
-    def _gotitem(self, key, ndim, subset=None):
+    def _gotitem(self, key, ndim, subset=None) -> "Series":
         """
         Sub-classes to define. Return a sliced object.
 
@@ -3983,7 +4000,7 @@ def drop(
         level=None,
         inplace=False,
         errors="raise",
-    ):
+    ) -> "Series":
         """
         Return Series with specified index labels removed.
 
@@ -4124,7 +4141,7 @@ def replace(
         )
 
     @Appender(generic._shared_docs["shift"] % _shared_doc_kwargs)
-    def shift(self, periods=1, freq=None, axis=0, fill_value=None):
+    def shift(self, periods=1, freq=None, axis=0, fill_value=None) -> "Series":
         return super().shift(
             periods=periods, freq=freq, axis=axis, fill_value=fill_value
         )
@@ -4183,7 +4200,7 @@ def memory_usage(self, index=True, deep=False):
             v += self.index.memory_usage(deep=deep)
         return v
 
-    def isin(self, values):
+    def isin(self, values) -> "Series":
         """
         Check whether `values` are contained in Series.
 
@@ -4239,7 +4256,7 @@ def isin(self, values):
         result = algorithms.isin(self, values)
         return self._constructor(result, index=self.index).__finalize__(self)
 
-    def between(self, left, right, inclusive=True):
+    def between(self, left, right, inclusive=True) -> "Series":
         """
         Return boolean Series equivalent to left <= series <= right.
 
@@ -4315,19 +4332,19 @@ def between(self, left, right, inclusive=True):
         return lmask & rmask
 
     @Appender(generic._shared_docs["isna"] % _shared_doc_kwargs)
-    def isna(self):
+    def isna(self) -> "Series":
         return super().isna()
 
     @Appender(generic._shared_docs["isna"] % _shared_doc_kwargs)
-    def isnull(self):
+    def isnull(self) -> "Series":
         return super().isnull()
 
     @Appender(generic._shared_docs["notna"] % _shared_doc_kwargs)
-    def notna(self):
+    def notna(self) -> "Series":
         return super().notna()
 
     @Appender(generic._shared_docs["notna"] % _shared_doc_kwargs)
-    def notnull(self):
+    def notnull(self) -> "Series":
         return super().notnull()
 
     def dropna(self, axis=0, inplace=False, how=None):
@@ -4421,7 +4438,7 @@ def dropna(self, axis=0, inplace=False, how=None):
     # ----------------------------------------------------------------------
     # Time series-oriented methods
 
-    def to_timestamp(self, freq=None, how="start", copy=True):
+    def to_timestamp(self, freq=None, how="start", copy=True) -> "Series":
         """
         Cast to DatetimeIndex of Timestamps, at *beginning* of period.
 
@@ -4446,7 +4463,7 @@ def to_timestamp(self, freq=None, how="start", copy=True):
         new_index = self.index.to_timestamp(freq=freq, how=how)
         return self._constructor(new_values, index=new_index).__finalize__(self)
 
-    def to_period(self, freq=None, copy=True):
+    def to_period(self, freq=None, copy=True) -> "Series":
         """
         Convert Series from DatetimeIndex to PeriodIndex with desired
         frequency (inferred from index if not passed).