Even for a cartoon character, going through puberty isn't easy for a young person. Andrew is learning that first hand as he experiences the nightmare that is growing up in this animated series geared toward adults. Along for the ride are friends Nick and Jessi, who develop a budding romance along the way. The comedy veterans who lend their voices to "Big Mouth" include John Mulaney, Nick Kroll, Maya Rudolph, and Jordan Peele.
- Main article: Episode Guide
|1||September 29, 2017||10|
|2||October 5, 2018||10|
|3||October 4, 2019||10|
- Nick Birch - Nick is a 12-year-old boy who lives in Westchester, New York and goes to Bridgeton Middle School. He is a late bloomer who has not started puberty yet. He is, however, very eager to start it. He wants desperately to start growing up but his parents still treat him like a baby.
- Andrew Glouberman - Andrew is your average horny, early blooming boy. To push him through the ordeal that's called puberty, a Hormone Monster pops up every once in a while.
- Jessi Glaser - Jessi is a young teenager who is starting to go through changes. As gruesome as puberty may be, she has the Hormone Monstress to cheer her on and give her advice.
- Jay Bilzerian - Jay is a loud, rambunctious, perverted, misogynistic, horny teenage boy who comes from a bad home. He wants to have sex with girls but right now, all he does is have sex with pillows.
- Missy Foreman-Greenwald - Missy is a thirteen-year-old girl who should not be fed sugar. Even though she is a brainiac and one to easily get a sugar high, her friends still love her.
- Maury - Maurice is the hormone monster for male puberty. He is very disgusting, perverted, and sex-obsessed. He pushes his clients into doing sexual things which more often than not get them into trouble.
- Connie - Connie is the hormone monstress for female puberty. Like Maury, Connie is brazen, slutty, and voluptuous. She can be very emotional and often gets into arguments with the clients, which almost always end with her and her clients crying.
- Matthew MacDell - Matthew is a gay kid at Bridgeton Middle School.
- Coach Steve - Coach Steve is a really stupid, messed up gym coach.
- Elliot Birch - Elliot is the effeminate, overly happy patriarch of The Birch Family.
- Diane Birch - Diane is the clingy and domineering matriarch of The Birch Family.
- Judd Birch - Judd is Nick's juvenile delinquent of an older brother.
- Leah Birch - Leah is Nick's level headed older sister.
- Lola Skumpy - Lola is an ugly, disgusting girl, who is very loud and crude.
- Devin - Devin is a mean bitch, who bullies other girls.
- DeVon - DeVon is the boyfriend of Devin and the token black guy.
- Lars - Lars is a depressing paraplegic boy in a motorized wheelchair.
- Caleb - Caleb is an imaginative boy with special needs.
- Lump Humpman - Lump is a stupid guy who goes to Bridgeton Middle School.
- Gina Alvarez - Gina is a Mexican girl with big boobs.
- Ali - Ali is a pansexual girl.
- Principal Barron - Principal Barron is the miserable old principal of Bridgeton Middle School, who hates her life and her job.
- Miss Benitez - Miss Benitez is a homeroom teacher at Bridgeton Middle School.
- Mr. Lizer - Mr. Lizer is a teacher at Bridgeton Middle School, who sexually harasses his female students.
- Rick - Rick is Coach Steve's adult hormone monster, who is really ugly and messed up just like him.
- Tyler - Tyler is a teenage hormone monster, who's going through puberty himself. He is very bad at his job.
- Mona - Mona is Missy's new hormone monster, who acts very similar to Connie only a lot crazier.
- Shame Wizard - The Shame Wizard is the embodiment of shame. He makes people feel ashamed of what they do.
- Depression Kitty - The Depression Kitty is the embodiment of depression. She makes people feel depressed.
- Detective Florez - Detective Florez is a cranky, grizzled old police detective.
- Detective Dumont - Detective Dumont is a stupid, silly old police detective, who works with Detective Florez.
- Dr. Wendy Ingle - Dr. Ingle is a children's doctor, who brings up his personal life and marital problems with his patients.
- Aiden - Aiden is Matthew's boyfriend.