Alter is both a surname and a given name. Notable people with the name include:
Surname:- Avraham Mordechai Alter (1866–1948), Hasidic rabbi
- David Alter (1807–1881), American inventor
- Dinsmore Alter (1888–1968), American astronomer and meteorologist
- Harvey Alter, American virologist
- Hobart Alter (1933–2014), American businessman
- Israel Alter (also: Yisraʾel Alter, 1901–1979), Jewish composer and last chief cantor in Hanover, Germany
- Jonathan Alter, American journalist
- Karl Joseph Alter, American prelate of the Roman Catholic Church
- Louis Alter, American composer
- Michael Alter, American businessman
- Moshe Jacob Alter, Yiddish poet
- Pinchas Menachem Alter, Hassidic rabbi
- Robert Alter, Biblical scholar
- Stephen Alter, American author
- Simchah Bunim Alter, Hassidic rabbi
- Tom Alter, Indian actor
- Yaakov Aryeh Alter, Hassidic rabbi
- Yehudah Aryeh Leib Alter, Hassidic rabbi
- Yisrael Alter, Hassidic rabbi
- Yitzchak Meir Alter (c. 1798 – 1866), Hassidic rabbi