Jazmine "Jazz" Fenton is a fictional character from the Nickelodeon cartoon, Danny Phantom. She is the intelligent oldest child of Jack and Maddie Fenton and the older sister of Danny Fenton.

Jazz, being the older sister and feeling the most rational of the family, takes it upon herself to be the "mature" figure, often criticising her parents obsession with ghosts and protecting her younger brother. While she may not know it, she often uses her intelligence as a means of superiority over others, going completely bonkers if she's shown to be wrong and often using her older sister status to "boss" Danny around, acting more like a mother than a sister. Simply put, she's more of an adult stuck in a teen's body. Ultimately, she means well, using her knowledge to point her parents in a more "normal" direction and keeping an overprotective eye on Danny, even if it sometimes is a constant annoyance to others.

Yet Jazz eventually developed as the show progressed, starting off as a rather snobbish genius who refuse to be assiocated with her parents while maintaining a serious attitude, only for her to later discover how much fun ghost hunting is and embracing it, as well as toning down her serious nature and discovering her inner child while still being her supportive self. Her sudden increased interest in ghosts has caused Jazz to imply or hint she is suffering from "Ghost Envy" when she states she desires to be a ghost to get her parents' attention. In addition, she develops a deep respect for her brother's selflessly heroic nature and attempts to support him.

As well meaning as she is though, she isn't as well experienced in ghost fighting as Danny and his friends (though she gradually improves), resulting in her helping Danny from the background by continuously covering his identity from suspecting eyes--particularly their parents. She is also terrible at giving ghosts names, (Crate Creep = Box Ghost, Lunch-A-Belle = Lunch Lady, Ghost X = Skulker, Creep Walkers = Sleep Walkers, etc.) and making puns. What Jazz lacks in ghost-hunting experience she more than makes up for with her intellect. A cunning strategist, she brings a new dimension to Team Phantom (with Danny and Sam considered to be physical threats, while Tucker is the technology expert) that can save them in the most unexpected times. Her strategizing skills showed to be useful when she went undercover to seek out Vlad's secrets in his castle, manipulated Freakshow into eventually gave Danny a suggestion that won him the battle with him, and concocted the plan to capture three ghosts and reversed their effects on the town.

She is apparently popular in her school and very social (though at one point in "The Ultimate Enemy", a group of girls walked away nonchalantly after she expressed her desires to reach a high ranking college) Which suggests that she may not have any friends. "Girls' Night Out" revealed Jazz as bad a singer as Tucker, Frightmare revealed that Jazz's worst fear/nightmare is being married to Dash Baxter and that her dream is to teach at Yale University as a professor, and it is hinted at in Reality Trip that Jazz has a case of "Ghost Envy" as through out her life the subject of ghosts has gained more of her parents attention then she has along with the fact that her younger brother has ghost powers.