Brad Alcerro is the main antagonist of the fourth season of the sitcom Sabrina, the Teenage Witch a role fulfilled by Libby Chessler in seasons 1 through 3. He is Harvey Kinkle's old best friend who moves back to Westbridge in the show's fourth season after living in Texas. Not much is known about Brad's life except for the fact that he has a stepfather. Brad is revealed to have a witch hunting gene, which makes his presence at Westbridge High a threat to Sabrina.
Brad initially disliked Sabrina, seemingly for no reason, until it was revealed by Hilda and Zelda that he is a Witch Hunter. Brad doesn't know what he is, though whenever he is around a witch or magic is used in his presence, he senses it and immediately becomes cautious, which is why he is constantly rude to Sabrina.
In the episode "Dreama, the Mouse", after Sabrina's tutee, Dreama uses magic in front of him, Brad declares his thinking that she is a witch which turns her into a mouse. Harvey manages to get Brad to Sabrina's house so they can revert his effects on Dreama. Sabrina and her aunts then try to remove Brad's Witch Hunter gene or else Dreama will be stuck as a mouse for 100 years. They are successful despite the fact that Sabrina had Spring Fever, and remove the gene, which is literally a pair of tiny blue jeans. Afterwards, Sabrina and Dreama are both free to use magic around him like they would any other mortal. Despite eventually losing the gene, he still remains a jerk to Sabrina and Dreama.
After the 4th season, Brad was one of several high school characters never seen or mentioned again. Presumably, he went off to college, away from Westbridge.