• Passing in a list of values with or without the index

import pandas as pd 
list1 = ["a","b","c"]
s1 = pd.Series(list1)
s2 = pd.Series(["a", "b", "c"], index = [1, 2, 3])

• From a dictionary. If an index isn't passed, the dictionary keys are used to create an index

import pandas as pd
d1 = {"a" : 1, "b" : 2, "c" : 3}
s1 = pd.Series(d1)

• From a scalar value. The value is repeated to match the length of the index, and the index must be provided.

import pandas as pd
s = pd.Series(1, index = ["x", "y", "z"])