Scott Dünbier covered this in great detail a couple of years ago on his blog so I'll do a quick recap and maybe add a few points that Scott forgot to mention:
Back in the late '90's, Scott was editing books for Wildstorm and asked Gil Kane to pencil this cover. Gil sent the pencils directly to me to ink because time was short. I faxed a copy of the pencils to Scott's office. We all hit the panic button: Kane drew Zealot, one of the WildC.A.T.S. fighting an alien, just like Scott asked him to, but for the alien, he drew a creature in a space suit, not a Giger/Movie Alien. In Gil's defense – since as Scott knows, I always side with creative people against management – I asked Scott if he mentioned to Gil that this was specifically one of the aliens from the movie franchise. In the most contrite voice I'd ever heard from Scott, he said, "Well, no..." Then, to extend his discomfort a little longer, I said, "Did you send him any reference for the alien?" "Well, no..."
Think about how long Gil had been drawing Science Fiction comics. For more than four decades, when an editor or a writer asked for "an alien", without supplying reference or directing him to a previous story or series, it meant that Gil was supposed to create a new alien.
Scott agreed but later quoted Arthur Adams' words of support, "What did Gil think this was, 'WildC.A.T.S. vs Make-up-your-own-alien?!"
Scott and I have had a couple of angry disagreements over the years, but this isn't one of them. He was reluctant to make this story public, even after Gil passed because he didn't want to embarrass an artist he revered. I pointed out that if he told the story correctly, he (Scott) was the only person who would look foolish. Every once in a while we have a laugh over it, and yes, I really did respond to his "What are we gonna do?" question with, "Whattaya mean WE, white man?" That was the first and probably the last time I've had a chance to quote that old Tonto punchline from MAD magazine. Most of you are probably too young to get the joke.