Yahtzee, of course. I know he's not a mainstream celeb, but he's a gaming one, so I say it counts.
Justin Bieber, so there's a disposable meatbag available when the cabin fever sets in.
John Stewart, for comedic relief.
Jack Thompson, for similar reasons to Bieber.
And Angelina Jolie, so I'm not the only female in the house and thusly the center of sexual tension.
*Edit* Hmm. After we've finally finished off the two meatbags, we'll be left with two males and two females, how convenient. I call dibs on Yahtzee! Too bad, Angelina!