Alt is a surname. Notable people with the surname include:
Albrecht Alt (1883–1956), German bible scholar and Protestant theologian
Carol Alt (born 1960), American model and actress
Ernst Alt, German Roman Catholic priest and exorcist
Franz Alt (mathematician) (1910–2011), Austrian-born American mathematician
Franz Alt (painter) (1821–1914), Austrian painter, brother of Rudolf
Rudolf von Alt (1812–1905), Austrian painter
Salome Alt (1568–1633), Austrian wife of Wolf Dietrich (von) Raitenau
Susanne Alt (born 1978), German female saxophonist
