Jennifer Tallulah Humphrey (b. July) is a main character in both the Gossip Girl and The It Girl novels by Cecily von Ziegesar. She is portrayed by Taylor Momsen in the tv series.

Jenny is the youngest main character in the Gossip Girl series. Though she lives on the Upper West Side in a beat-down apartment with her scruffy father, Rufus, and older poet sibling Dan Humphrey, she is always trying to fit in with the more popular girls at her exclusive private girls' school, Constance Billard, where Upper East Side princesses like Blair Waldorf and Serena van der Woodsen attend. She idolizes sexy and wealthy Serena van der Woodsen, to the point of being accused of "humping" her. Jenny is more commonly known for one thing, however: the size of her breasts (DD). They have drawn the attention of many a boy and are the bane of Jenny's existence, particularly when she is sexually assaulted by Chuck Bass in a bathroom at a party. She is 5 feet tall and has curly brown hair.

Jenny dated Nate Archibald (unwittingly helping him cheat on his on-again, off-again girlfriend Blair Waldorf), but they broke up because Nate was still in love with Blair. Then she dated the enigma, Leo, with whom Jenny soon broke up with because of his poor living conditions. After a series of embarrassing situations and lessons in becoming her own person, including an appearance in a teen magazine wearing only underwear, and staying the night in the Plaza Hotel with popular band, The Raves, Jenny went off to attend Waverly Academy boarding school. She is now starring in her very own book series, The It Girl, which features her as the new girl at Waverly Academy, whose resemblance to a girl by the name of Tinsley may bring troubles in books to come.

In The It Girl, Jenny tries to reinvent herself as a "popular and sophisticated city girl" and leave behind the girl she was at Constance. When Jenny arrives at Waverly, she finds the students even more attractive, athletic, and intimidating than she imagined. She meets Yvonne Stidder, a jazz ensemble geek, and decides not to hang out with her after her quick tour of the campus. Jenny then meets her two new exceptionally beautiful and popular 11th grade roommates: lithe and blonde Southern girl Callie Vernon, and red-headed, green eyed, and sophisticated New Jerseyan Brett Messerschmidt. She quickly learns that she has replaced their old best friend: extremely attractive and notorious Tinsley Carmichael. Jenny can't help but feel that sleeping in such a lucky bed must rub off. Callie and Brett seem to have an inside squabble going on about the expulsion of Tinsley from Waverly, while Jenny can't help but be placed in the middle. One evening, after Callie's boyfriend Easy Walsh sneaks in to their room to hook up with Callie, Easy finds himself sitting on Jenny's bed after Callie has left in a rage. Just as the two were beginning to talk, the dorm mistress's stoner husband, Mr. Pardee, finds Easy in the girl's room in his underwear. Easy and Jenny are given a formal hearing for this. This incident only furthers the problems between Brett and Callie. Callie wants Jenny to cover for her, telling the student council that Easy was there to see Jenny, not Callie. Brett thinks that Callie should stick up for herself and not allow Jenny to be expelled. However, Jenny wants to be liked and decides to think about taking the blame at the hearing. Callie sucks up to Jenny and even asks that she and Easy pretend to like each other, just so the whole situation would look believable at the hearing. Callie never expected the twin artistic souls to become truly infatuated with each other. Also unexpected is the return of Tinsley Carmichael, which occurs in Book 2: The It Girl: Notorious. In Book 5, The It Girl: Lucky, she is expelled because she is held responsible for burning down the Miller barn but someone bribes Mrs. Miller and Jenny does not get expelled. Her friend, Brett tells her this and the both think that Jenny has a secret admirer, but everyone thinks it was either Easy or Jullian (her supposed boyfriend).

Jenny Humphrey is the daughter of rock 'n roll player Rufus Humphrey, and younger sister of Dan Humphrey. She and her family reside in Williamsburg, Brooklyn. Her mother, Alison, left them temporarily to fufil her dream of becoming an artist. Jenny always wants to fit in and even once got angry at her mother for buying her vintage shoes, exclaiming "Mom, kids at school shop at places like Saks and Bendel's, I can't be walking around in someone else's old shoes." She has long blonde hair and attends the Contance Billard School for girls.

Jenny Humphrey is introduced in Season 1. She is a pretty, blond freshman at Constance Billard. She is always desperately trying to fit in with the it crowd. She has been the pawn of the main characters of many of the main cast, especially Blair Waldorf, from episodes one to nine. However, when Blair's affair with Chuck Bass is let known, Jenny becomes increasingly popular. The cool kids and former friends of Blair shun her and bring Jenny into their inner Queen Bee circle in Episode 13.