Eugene Pool is Sabrina's biology teacher, her favorite teacher, during her sophomore year of high school. He also teaches Sabrina martial arts, in one episode.
Since teaching doesn't pay much, he sometimes does extra odd jobs for and around the school to make extra money, once "discovering" how to created gold by solving an alchemy equation, but he eventually forgets it. He disappears, after Season 1, when Sabrina passes his class. He is replaced in the main cast with Willard Kraft. His name is a pun on the scientific term, "gene pool." His screen name is "BioStud".