Jessica Phyllis "Jessi" Glaser is arguably the main female character in Big Mouth. She is a sarcastic, popular and intelligent girl who has somewhat physical/emotional development in early terms and she is a good friend of Andrew Glouberman, Missy Foreman-Greenwald, Nick Birch and Jay Bilzerian.
Jessi comes from a dysfunctional Jewish family where hostility and arguments is the norm. Her mother was unfaithful in her marriage (having had an affair with a local cantor) and her father has a severe dependency on drugs, particularly marijuana, which has caused Jessi to "act out" in a number of ways, including her on-again-off-again relationship with Jay Bilzerian and attempting to flee her old life to run away with him.
Jessi is a somewhat tall redhead with red hair that is usually tied in a ponytail with bangs hanging over her forehead, brown eyes and she frequently sports deadpan expressions. Although, she is more physically developed than some of her peers (particularly Missy Foreman-Greenwald), she is perpetually insecure of the small size of her breasts, particularly in comparison to Fatima, the romantic protagonist of The Rock of Gibraltar.
She is almost always seen wearing a lavender-colored blouse on top. bright crimson leggings and black shoes.
Jessi is an intelligent girl with a dry sense of humor, although despite her negative attitude, she's very likable and shows strong affection towards her friends (despite that she might poke fun at them from time to time). She is in recovery from depression, as well as issues surrounding her family, and attends regular sessions with a therapist.