Caleb is a fictional character played by Nathan Fillion in the television series Buffy the Vampire Slayer created by Joss Whedon. The character is a sadistic sociopath with a pathological hatred of women.
According to Whedon, the character was introduced because the mutable, non-corporeal nature of the First Evil "meant that we didn't really have anything to push against. We needed... a sidekick. Somebody physical that we can see from episode to episode." Whedon describes him as "the creepiest priest", adding, "he is the most bald-faced misogynist we've had since, well, since last year, with Warren."
Prior to becoming the right-hand man of the First Evil, Caleb was a defrocked priest and serial killer responsible for the deaths of at least two girls, whom he lured with his stirring sermons, masculine charm, and rugged handsomeness.
Despite not appearing until the last five episodes of the series, the character is revealed to be one of the prime movers for the events of the seventh season. In an effort to eliminate all threats to the First Evil's resurgence, he directs hordes of Bringers to systematically kill Potential Slayers around the world. He also orders the bombing of the Watchers' Council Headquarters in London, causing the deaths of Quentin Travers and all Watchers and Council Operatives present, and arranges for a fellow prisoner to attack Faith in a Los Angeles prison.
In the episode "Dirty Girls", Caleb attacks the Scooby Gang in person. He murders two potential Slayers (one being Molly; one of the first potentials to appear in the series), breaks the arm of another (Rona) and effortlessly defeats Buffy Summers, Faith Lehane, and Spike. Before the Gang retreats, he also violently blinds Xander Harris in one eye by forcing his thumb into his left eye socket.
The character dies in the last two episodes of the series. In "End of Days" and "Chosen", Buffy, with the assistance of the newly arrived Angel, kills Caleb in a final confrontation. With Angel watching, Buffy pierces Caleb's abdomen with the Scythe, apparently killing him. Much to their shock, Caleb is revived with another power transfusion from the First Evil and immediately knocks Angel unconscious with a devastating blow. Buffy and Caleb resume their fight. However, Caleb's injuries weaken him. In the end, Buffy cuts Caleb in half vertically, from his crotch to his torso, actually castrating him and finally killing him. Angel comes to ready to fight Caleb and discovers him cleaved, Buffy quips "he had to split", and both share a much deserved laugh.