People have either gone for the He's a robot Or he's a super mutant. Did you ever think that he is a horribly disconfigured ghoul in order to maintain order over New vegas. I mean imagine what would happen if people find out a ghoul is running all of New vegas? To be the Robot thing sounds a little ehhhh i mean the've done that already not going to say where or when but Its been done twice already.
*Sigh* Maybe its just me and my being a fan boy, but heres the scoop.
Spoiler
Mr. House was supposedly frozen just prior to the war and has a hand in why the Las Vegas area was not hit by nuclear bombs. Now, in Dev Diary....one I believe, we see a VERY brief glimpse of Mr House and his face on a computer screen in the top of the Lucky 38. Now, this implicates that he is either
A. A super computer sort of like the ZAX
B. A brain/computer hybrid
C. What Gabriel77dan (sp?) and a few others frequently states. Mr House, like Howard Hughes (Whom Mr. House is based on), is a massive germaphobe and is in isolation in a secure room and communicates with you via console.