Actor Douglas Rain, who voiced the deadpan computer voice of HAL 9000 in 2001: A Space Odyssey, died on Sunday of natural causes. He was 90 years old.

Although he had a decades-long list of stage, film and television credits, Rain was best known as the voice of the futuristic but malfunctioning computer. In Stanley Kubrick's 1968 movie, HAL 9000 was an integral part of a deep-space mission investigating an extraterrestrial artifact known as the Monolith.

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The autonomous computer aboard the Discovery ultimately went against its programming and turned homicidal, killing all of the crew save astronaut Dave Bowman, played by Keir Dullea. Rain's iconic line, "I'm sorry Dave -- I'm afraid I can't do that," became an oft-cited phrase in pop-culture conversations.

Rain reprised his role as HAL in Peter Hyams' 1984 sequel, 2010: The Year We Make Contact, which reunited him with Dullea. The reason for HAL's malfunction was cited as contradictory programming.

Rain was born in Winnipeg, Manitoba. Prior to 2001, Rain was best known for his Shakespearean roles in an Ontario stage company. He had expanded his presence into television in the 1960s, where he performed in productions of Twelfth Night and Henry V, and continued acting into the 1990s.

(via Deadline)