He serves as one of the primary antagonists of the series.
Lionel Herkabe was born on July 8, 1963 to John and Ida Herkabe. Herkabe was a Krelboyne in his youth and attended Princeton and earned a double doctorate in business at Harvard. His life all started going downhill when he quit a government think tank job to start a dot com, with that he dropped from one time net worth 2 million to a mere $137. He was previously married, but his wife divorced him after his poor decision. He first became a teacher at the school in the episode Emancipation. Following the events of Caroline Miller giving birth in the episode High School Play, someone had to fill in for her. However, instead of someone equally as nice and caring as she was, Mr. Herkabe came in and immediately started mistreating his students. Despite being a former Krelboyne and having suffered the same bullying as a child that his students do today, he was absolutely disrespectful and cruel to all of his students and tried making them all feel terrible.
Mr. Herkabe very quickly became Malcolm's Arch Enemy and did the same for all the other students. He shares the same traits and personality as Malcolm, but he hates him profoundly and goes out of his way to try to kick him out of the Krelboyne class. He brought in a young boy genius named Barton in the hopes of kicking him out of the class so he doesn't worry about him later on. Unfortunately, he not only proves to be helping hand to Malcolm, but also his father hated how Herkabe was treating him like a piece of glass and pulled him out of the class for him to be a normal kid.
He is generally emotionally abusive towards his students. In his first appearance he set up a board at the front of the classroom, which ranked each student from smartest to least based on extremely small decimal point differences between their relatively equal grades. This caused the Krelboyne's to become so stressed they could no longer function properly, with Lloyd not even being able to remember his own name. He was particularly cruel to Dabney Hooper. He announced to the entire class that Dabney was an emotionally needy bedwetter who did not receive affection at home. He then advised him not to attempt to seek said affection from him. He also caused Dabney to break down into tears by moving Dabney's name down nine spots on the board after he'd given an answer about the book "Moby Dick".
In the episode Humilithon, Malcolm and the other Krelboynes graduated middle school and went onto North High School. On the same year, Mr. Herkabe transferred schools and went to the same one Malcolm did, just so that he could continue harassing him. He also had the job of giving orders to the parent volunteers at the school, meaning that he could also harass Hal and Lois for working at the school.
In the episode Academic Octathalon, both he and Lois blackmails Malcolm in joining the Octathalon with the Krelboynes. When he discovers that it's an all out cheat race, he makes everyone pay by secretly stealing the results of the Octathalon which ends predictably in disaster. This was the only time Herkabe was actually nice to Malcolm and didn't harbor any antagonistic feelings for him, until he discovered exactly what Malcolm had done.
He was shown again in the episode Tiki Lounge, where he puts Malcolm in the Boosters Club trying to go after him again.
In the episode Malcolm Defends Reese, Herkabe convinced Malcolm to fail all of his classes intentionally, on the condition that he leaves Reese alone; this was so that Herkabe could keep his crowning achievement: being the record-holder of the school's highest GPA and the award that came with it. However, Herkabe makes a big mistake: in his gloating, he casually confesses to Malcolm that during his senior year, he cheated his way out of gym class and lied about it for years in order to protect his GPA award. Malcolm gets his revenge on him by telling the school principal, Mr. Hodges (Steve Vinovich) about it. The next day, Herkabe is humiliated when he loses his GPA award as his punishment for failing gym and lying about not taking the course for years. The GPA award is returned to Edna Thornby, a blind and clubfooted woman who managed to pass gym despite her disabilities. Herkabe was last seen being humiliated by an overly excited Reese who's been tossing dodge-balls at him out of revenge for all the humiliation he's endured. After that he wasn't shown again.
Herkabe at heart, is a conniving, vile, hateful, despicable man who shows complete disrespect for his students. He attacks them with insults and offensive comments that mainly focus on their intelligence and overwhelms them all with tons of mental challenges that are too much for them to handle. However, Malcolm is the only one who is seen to handle Herkabe's mental abuse due to dealing with a similar one from Lois.
However, Herkabe's conniving and despicable ways came back to haunt him when Malcolm exposed his horrible secret in flunking Gym and lying about not taking the course for years to Mr. Hodges, North High School's principal. After getting his award revoked and taken away, Herkabe tried to make one final comeback at Malcolm by taking Gym. However, Reese, out of gratitude to his brother, humiliated the uncoordinated Herkabe by pelting him with dodge-balls. Even the class joined in on the fun.