Ivan Reitman (born October 27, 1946) is an American-based Canadian film producer and director. He is known for the comedies he has directed and produced, especially in the 1980s and 1990s.

Reitman was born in Komárno, Slovakia, the son of Klara and Leslie Reitman. Reitman's parents were Jewish; his mother survived the Auschwitz concentration camp and his father was an underground resistance fighter. His family emigrated to Canada in 1951. Reitman attended Oakwood Collegiate in Toronto and was a member of the Twintone Four singing group.

Reitman's first producing job was with the then-brand new station CITY-TV in Toronto. CITY was also the home of the first announcing job of his later friend and collaborator Dan Aykroyd. However, Reitman's tenure at CITY was short and he was fired during his first year by station owner Moses Znaimer.