A number of historical people were named Alexander I :
- Alexander I of Epirus king of Epirus about 342 B.C.
- Pope Alexander I, pope from 106 to 115.
- Alexander I of Scotland (c. 1078-1124), king of Scotland.
- Russian Tsar Alexander I (1777-1825), emperor of Russia.
- Alexander I Jagiello, (1501-1505), king of Poland and grand duke of Lithuania of the Jagiello Royal family.