Males:
James Earl Jones: Come on bring Darth Vader to the Wasteland.
Anthony Hopkins: Come on bring Colonel John Frost to the Wasteland (come on you thought I was going to mention another role )
GroovyBruce.. which is his twitterhandle: Bruce Campbell: Ash from the evil dead series.. The man who was destined to play Benny :-/
Sam Rockwell, the man with the crazy scheme..
Vin Diesel: Yes I know the guy is usually known for his action parts.. but the guy did start out as a legit actor... and his grating voice would fit FO well.
Chris Rock: In his stand up anger mode.. (FO needs more biting sarcasm from its NPC's in its current run)
Females:
Ellen Page: Underestimated talent.. can play anything, but (me thinks) thanks to her her agent she is (still) typecast as the rebel teenager (she's 22 btw).. Could work well as a companion.
Controversial: Merryl Streep: She is so versatile but never (to my knowledge) did any CG work.. would be interesting.
Zooey Deschanel: Hippy, crazy... peppy.... she can voic act it.
Tricia Helfer: Overused yes.. but she.. I don't know has this je ne sais quoi which make her perfect to play an AI..
Gillian Anderson: Come on who doesn't want Dana Scully in the Wasteland..
Jenniffer Tilly: ..... that..... voice.... (not being positive here... but if would fit a FO character well)