Yep, there are several "alien" characters in Grand Theft Auto V that bear a distinct resemblance to the Xenomorph!
First came across them when involved in a car chase through a film studio — several actors dressed as green aliens with elongated skulls jumped out of the way as I tore between the stages.
A later mission had me smoking some pretty potent pot and hallucinating that similar aliens were trying to abduct me (forcing me to mow them all down with a minigun).
EDIT: The comments below got a bit sidetracked into general GTA V discussion, so I thought I'd point out for those that might be worried — it's all spoiler-free!