Douglas Rain (born 1928) is a Canadian actor and narrator. He is primarily a stage actor, but his best known film role was as the voice of the HAL 9000 computer in 2001: A Space Odyssey (1968) and its sequel 2010 (1984).

Rain was born in Winnipeg, Manitoba. He studied acting at the Banff School of Fine Arts in Banff, Alberta as well as in London at the Old Vic School. As a stage actor, his long association with the Stratford Festival of Canada that spans more than four decades. He has performed in many diverse roles on stage, most notably recognized for his performance at Stratford, Ontario in Henry V which was made into a television production in 1966.

Rain was also nominated for Broadway's 1972 Tony Award as Best Supporting or Featured Actor (Dramatic) for his performance in Vivat! Vivat Regina!