Gordon Carroll, David Giler, Walter Hill. Not to mention Ron Cobb, HR Giger, numerous modelmakers, and, well, Sigourney Weaver. They were at the spearhead of the Alien series from the first film onward (in varying capacities) and they ended up deciding the trajectory of the series. The legions of Dark House employees working on the comic books, not so much.
I didn't know Jean-Pierre Jeunet was such an avid reader of the AVP Discussion Forum - I loved Delicatessen, monsieur!