Whether or not you've heard Dan O'Bannon's name before, you're a fan of his work on Dark Star, Star Wars, Alien, Lifeforce, Screamers and Total Recall. He passed away yesterday, but his legacy on lives forever.

Probably O'Bannon's biggest contribution to science-fiction movies is his work on the screenplay of Alien, which started life as his script Star Beast. According to Empire Magazine, O'Bannon's script was the movie's first draft, although others later worked on the screenplay. And Empire says he brought over several of his colleagues from Alejandro Jodorowsky's abortive film Dune to Alien.

But prior to Alien, O'Bannon was co-writer and visual effects supervisor on John Carpenter's loopy Dark Star. And he also played Sgt. Pinback, as seen in the clip above. And O'Bannon worked on the original Star Wars, helping to craft those great computer graphics of the Death Star plans and the attack run — and according to this poster at IMDB, he's also in the movie, as one of the technicians in the Rebel Base during the Battle of Yavin.