Althoff is a surname. Notable people with the surname include:
Bobbi Althoff (born 1997), American podcaster and social media personality Ernie Althoff, Australian musician Friedrich Althoff (1839–1908), Prussian Minister of Culture Kai Althoff (born 1966), German painter Pamela Althoff (born 1953), Republican Illinois State Senator
See also Althoff Studios, an erstwhile (1939–1946) Film Studio in Berlin Babelsberg (Germany), later property of DEFA Althoff Catholic high school, high school in Belleville, Illinois