Screenwriter Dan O’Bannon, best known for the 1979 science-fiction hit Alien, died on Thursday at age 63 after a brief illness. After cutting his teeth as co-writer of director John Carpenter’s 1974 sci-fi comedy Dark Star, the St. Louis-born O’Bannon made his breakthrough with his script “The Star Beast,” co-written with Ronald Shusett, which became the basis for Ridley Scott’s outer-space thriller Alien. O’Bannon went on to work on such sci-fi movies as Lifeforce, Invaders From Mars, and Total Recall and made his directorial debut with 1985’s The Return of The Living Dead. In 2004, he returned to the Alien franchise as co-writer of AVP: Alien vs. Predator.