Who would you most want by your side in a post-apocalyptic, alien-run Earth? You have five options. Also, this question only applies to Tom Cruise.
Cruise is headlining a developing Joseph Kosinski sci-fi piece, Horizon, in which he'll play a globetrotting electronics repairman who is reponsible for keeping the human race alive. If this sounds somewhat familiar, you might have known about the project back when it was still advertized under its original name: Oblivion. That title, however, has been sent into... well, you know.
In the film, Cruise's character will have a right-hand woman: this is one of the two Horizon roles currently in contestion for a handful of actresses. Those included: Jessica Chastain (The Tree of Life and The Help), Olivia Wilde (who has been expanding her reputation beyond House with Tron: Legacy—also directed by Kosinski—and Cowboys & Aliens), Sundance darling Brit Marling (who will play opposite Alexander Skarsgard in the upcoming The East), Olga Kurylenko (Quantum of Solace and Centurion) and Noomi Rapace (the 2009 Girl With the Dragon Tattoo trilogy and Ridley Scott's upcoming Alien prequel, Prometheus). The other major Horizon role looking to be filled is that of Cruise's character's deceased fiancee (who will presumably manifest in dream sequences, flashbacks, hallucinations, or maybe your odd hologram).