Allistair Tenpenny is the wealthy proprietor of Tenpenny Tower in the game Fallout 3. He is the main business interest behind the destruction of the town of Megaton, and one of the most prominent side villains in the main game. Allistair has an uppercrust, snobby demeanor, and looks down on those who he considers beneath him, such as the residents of Megaton and the local ghoul population. He even goes so far as to suggest the erradication of both, sending his accomplice Mr. Burke to scout Megaton for willing contractors.
Mr. Tenpenny is a businessman at his core, and most of his evil deeds are motivated by profit and a desire to satisfy his client base. He wishes to obliterate Megaton for the simple cause of he and his clients considering it unattractive and view obstructing.
Mr. Tenpenny is also a prominent ghoul biggot, meaning he considers ghouls unsavory and less than human on the sole premise of their appearence. While he does hold biggoted views himself, he is not averse extending his services to a ghoul clientelle, as long as it does not interfere with his already established customer base. Because of this, the player has the option to convince Tenpenny to take the local ghoul population lead by Roy Philips as clients, after weeding out the tower's most stubborn biggots.
Allistair's biggoted views and elitest attitudes have earned him many enemies, particularly among ghouls. One ghoul named Mr. Crowley may even commission the player to assassinate Mr. Tenpenny, though their are also alterior motives involved in that assignment. Also, even if the player peacefully resolves the conflict between Roy Philip's group of ghouls and the residents of Tenpenny Tower, Philip's ghouls will eventually kill Tenpenny and all other non-ghouls living in the tower (unless the player is using a mod to override this event,) and it is never truely revealed who is responsible for the events that lead to this revolt.
Though Allistair is a cold and ruthless business man, and an arrogant snob, it is worth noting that he can be reasoned with, and the player may actually play the entire game making non-evil and good choices while maintaining a good relationship with Tenpenny. This causes his level of villainy to be dependent on player choices.