Bob, often written as BOB or Killer BOB, is the primary villain in the TV series Twin Peaks. He is portrayed as a malevolent entity who possesses people and feeds off their garmonbozia (pain and suffering). He was played by Frank Silva.
Bob possesses people and uses their bodies to murder and rape. He is an evil spirit of some kind, who has a connection to the woods and the owls outside the town. Everytime BOB kills someone, he places a letter underneath the victim's nail to spell out his real name "ROBERT".
Bob was once human; in his corporeal form, he was a serial killer whose partner in murder was a man named Mike (Al Strobel). At some point, Mike had a religious epiphany and repented, cutting off his own arm to rid himself of his "Fire Walk With Me" tattoo, which symbolised being touched by an "evil one". When Bob would not repent, Mike killed him. Bob's spirit remained however, and possessed Leland Palmer in order to continue his spree. Mike searched for Bob, aware that he was still killing, but unable to tell who his host was.
Bob's victims are not fully aware that they are possessed. Leland Palmer was possessed by Bob when he was still a boy. As an adult, Leland molested, raped and eventually murdered his daughter, Laura, all while under Bob's influence. It is implied that Laura allowed herself to be killed, because she knew that death was the only escape from being Bob's next host. Bob's bloodlust took over and he killed Laura through Leland, robbing himself of his new chosen host body.
By the end of the series (including the prequel film), Bob is known to have killed at least four people through Leland: Teresa Banks, Leland's mistress; Laura Palmer, his daughter; Jacques Renault (though it is debatable whether "Leland" or "Bob" did this one); and Madeline Ferguson, Leland's niece by marriage. In the final episode, Bob seems to be absorbing the soul of Windom Earle in the Black Lodge.
Bob possesses several people during the show's run, and the final episode of the show climaxed with Agent Dale Cooper (Kyle MacLachlan) being possessed by Bob.
Bob is a symbol of the evil that can lurk beneath the surface of apparently ordinary people. FBI agent Albert Rosenfield articulates this at one point, suggesting that Bob is not a real entity unto itself, but rather an embodiment of "the evil that men do"
company.