A Marvel movie does not get made unless Stan Lee makes a cameo. It's a fact. Think of any recent Marvel movie (what I like to call "the good ones") and Stan Lee is in there basically being Stan Lee. It doesn't matter what he's doing. He's just being Stan Lee. In Guardians of the Galaxy he was Stan Lee in Space and James Gunn wanted to kill him.
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Really! Not in the commit homicide sense but in a movie sense. Lee is usually featured as a bystander or at most a gag. He generally has little to no bearing on the story. In GotG he plays a citizen present during a crowd scene on Nova Prime.
Gunn's idea as shared by News-A-Rama was that Lee would actually be featured as part of The Collectors' Collection. The same collection that featured Howard the Duck, Cosmo the dog, and what appears to be an assistant that didn't work out.
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The original idea was that Lee would be in one of those same containers and when the Infinity Stone goes off, instead of getting his freedom like Cosmo and Howard, he meets his end. Gunn's idea included Lee's severed head rolling across the screen.
Bru-tal.
As anyone who saw the movie can attest, there was no rolling head of Stan Lee. Only a scene of a liberated Howard the Duck having a drink and hinting at a comeback. Which is pretty good I guess.
Catch Stan Lee being alive and stuff in Guardians of the Galaxy which is currently out on Blu-Ray and DVD.