In Buffy: The Vampire Slayer season 7, the Scooby Gang faces off against the First Evil and its right-hand man, Caleb, a seemingly ordinary human with mysterious strength. The First Evil, a.k.a. just the First, originally appears as a monster of the week in Buffy: The Vampire Slayer season 3, episode 10, “Amends.” It manipulates Angel by taking the forms of people he killed, prompting him to attempt suicide, but he thankfully fails.
The First returns in Buffy: The Vampire Slayer season 7, the show’s final season. It’s trying to destroy the Slayer line after Buffy’s friends brought her back to life a season earlier, disrupting the natural order of things. The First takes the appearance of people who have died but doesn’t have a corporeal form. The Bringers—humans with their eyes cut out who are nonetheless capable fighters—do its dirty work, including killing Potential Slayers. Caleb (Nathan Fillion) is first introduced in Buffy: The Vampire Slayer season 7, episode 18, “Dirty Girls.” He’s a misogynistic ex-preacher serial killer working for the First Evil but hasn’t been cut up like the Bringers.
Caleb is a better fighter than the Bringers, and potentially more physically powerful than Slayers. During his first appearance, he displays some of this strength when he stops Potential Slayer Shannon from grabbing the wheel of his truck, then burns her, stabs her, and pushes her out of the moving vehicle. But this is nothing compared to the damage he does later in the episode when he faces off against Buffy and her friends.
How Powerful Caleb Is Compared To Buffy
“The Slayer must indeed be powerful,” Caleb says to Buffy upon their first meeting, before hitting her with a punch to the face that sends her flying across the room and into a wall, knocking her unconscious. He then goes toe-to-toe with vampire Spike, Slayer Faith, and several Potential Slayers. Using his bare hands, he breaks one Potential’s arm and another’s neck. Buffy manages to get up and square off with him again. This time she’s the one who sends him flying, but he’s not down nearly as long as she was. In fact, it’s only a few seconds later when he uses his thumb to poke out Xander’s eye.
It’s obvious Caleb is more than just a regular human, but it isn’t initially clear what he is. He beats Buffy again in season 7, episode 19, “Empty Places,” but at the end of episode 20, “Touched,” he seems weaker. It’s not until episode 21, “End of Days,” that the audience learns Caleb is just a human who can access the First Evil’s powers by periodically merging with it. The First says he is “the only man strong enough to be my vessel.” Maybe the First regards Caleb with such renown because of his religious fervor or his pre-existing physical strength. Or maybe the First is just trying to butter him up.
They merge again and the First enters Caleb, turning his eyes black briefly. At the end of that episode, he can once again fight blow-for-blow with Buffy. But this time, she’s ready, and she slices him across the stomach, seemingly killing him. He does get back up a few minutes later, black goo dripping from his eyes, an apparent side effect of the First having to resurrect him. After another short fight at the beginning of “Chosen,” the Buffy: The Vampire Slayer series finale, Buffy cuts him in half, finally killing him. This proves that, even at his full power, Caleb isn’t truly stronger than Buffy. He demonstrates, however, that sometimes the scariest monsters are just humans.