Maybe a Mexican actor like Cheech, or Machete.
Personally I'm kind of hoping it's not someone obvious -- a big actor with a "I'm an adroid!" neon sign pointing at his/her head. But it's always a guessing game with the android, except for Alien, where the idea was a surprise. In Aliens, they didn't waste much time telling everyone that Bishop was a synthetic -- sorry, artificial person. By the time we got Call, I kind of wished they'd drop the trope. Then Prometheus came out and I fell in love with the idea again. There was no guessing. David was an android and loving it.
Still, now that we've come to expect an android to be in the films, I wonder how they'll go about it. Will they secret one in and risk it feeling cliche? Or will they state that this guy over here is one at the start and settle for complacency and regularity? I know that if they left out androids altogether it'd feel like something was missing, but perhaps they could back peddle away from the post-humanism concept of the android with a soul and revert to the machine-like Working Joes. Something robotic and uncanny. Those things were arguably as unsettling as the alien, but in a completely different way, and I think it'd add a nice dimension to the horror. The thing doesn't even have to go haywire. Just be creepy. That Tommy Wiseay recommendation is sounding better and better...