Steve Buscemi. I don't care how, I just want to see the guy get killed by an xeno. He just seems like the kind of guy that would suffer that sort of horrific end.
Emily Blunt. Female marine, or maybe even an adult Newt. Either way, I'd like to see her in this.
Aldis Hodge. Great actor who I think would fit in well in the Alien universe. He has the bonus of not doing any sci-fi before, and I'd love to see him in the genre. Plus, every Alien film has had at least one cool black guy. Parker, Apone, Dillon, Christie, Idris Elba's Captain(don't remember the captain's name, but he was cool). I think that for Alien 5 to truly fit into the franchise, this tradition must continue. It would be nice to have the black guy live this time, but I'm certainly not going to argue with tradition if the script calls for him to die horribly.