Hormone Monsters are monsters that aid human beings as they go through puberty. Although they are mainly for teenagers going through regular puberty, there are other hormone monsters that assist adults people with adult versions of "puberty", such as menopause and impotence.
- Maury - The main hormone monster. He is the monster of male puberty. He is a crude, perverted, sexually driven nymphomaniac, who urges his clients to have sex with their love interests. His unhealthy obsession for sex causes him to mislead his clients into making poor decisions that get them in trouble.
- Connie - The secondary hormone monster. She is the monster of female puberty. She is bitchy, brassy, and rude. She is very emotionally distraught and she tends to get emotionally invested with her clients. Connie also tries to make her clients act out and disrespect their elders.
- Rick - The hormone monster of adult male puberty. He is very old and disgusting and rather messed up in the head, much like Coach Steve. His goal is to make his clients have sex with people. After he finishes that, he considers his job to be done and then leaves.
- Tyler - A second hormone monster for male puberty. He is new to the job, shown by his ignorance and young age and is sort of going through puberty himself.
- Bob - A this hormone monster for male puberty. He is a sad, self-deprecating guy, who's terrible at his job and is well-aware of it.
- Lorraine - A second hormone monster for female puberty. She is a ditzy, flirtatious woman, who Maurice often hits on.
- Gavin - A third hormone monster for male puberty. He is a very confident man who is at the top of his game. Maurice envies his success and Nick desires his assistance.
- Stan - A second hormone monster of adult male puberty. He went to Las Vegas once and doesn't like dealing with The Shame Wizard's shit.
- Menopause Banshee - A hormone monster of adult female puberty. She is an old banshee, who is the monster of menopause.
- Mona - A second hormone monster for female puberty. She is very similar to Connie in that they both act the same and serve the same role in the series.
- A common rule is that hormone monsters are completely invisible to anyone, who hasn't been assigned to that specific monster. However, a small handful of characters have very clearly seen and interacted with hormone monsters that aren't theirs. Such characters include Caleb, Lars, and Jew Fishman.
- In "Smooch or Share", it is revealed that all of the hormone monsters swear a jizzocratic oath.