Jennifer Check (Megan Fox) is a popular girl that is turned into a succubus by a satanic ritual in the 2009 horror-comedy Jennifer's Body.
The movie is told through the perspective of Jennifer's best friend, Anita "Needy" Lesnicki (Amanda Seyfried). Jennifer starts out as a cheerleader and a stereotypical popular girl. She uses her good looks and sexuality to get whatever she wants and takes it for granted that no one will say no to her.
She is kidnapped by a band and sacrificed in a satanic ritual that gives them fame and turns her into a succubus. She continues to use her sexuality to draw men in and consume them.
Throughout it all, Needy is the only person that she seems to truly care about. Their friendship is shown as being unusually close from a very young age when they would play boyfriend and girlfriend. They seem to have a psychic bond. Later, we learn that that bond is also occasionally sexual, and in one of the more memorable scenes Jennifer says the line "I go both ways", though the word bisexual is never said out loud.
Jennifer is jealous of Needy's relationship with her boyfriend, Chip, and lures Chip away and eats him. This proves to be the final straw for Needy, as she then kills Jennifer.