Jimmy is the father of Jess Mariano. He is described by Luke as a no-good loser, who abandoned his wife and kid. Jimmy seems insecure, kinda rattled with a frenzic energy, but also with the best intentions at this point in his life. His family life in California with Sasha and her daughter seems fairly stable and he also owns his own business at Venice Beach.
Jimmy is first introduced when Jess's mother calls Luke to ask him to take care of Jess. The following year Jimmy mysteriously shows up in Stars Hallow and when Luke finds out he tells him to stay away from Jess. Jimmy doesn't listen and goes to see Jess anyway and when Jess finds out Jimmy is his father it is a big shock.
That night Jess and Luke get into a fight that ends with Luke throwing Jess out. Jess then leaves at the end of Season 3 to live with Jimmy in Venice Beach CA. Jimmy tries to tell Jess he can't stay with him and his roommate Sasha but in the end he lets Jess stay.
- The character was intended to be a main character with Jess in a new WB show entitled Windward Circle (a spin-off from Gilmore Girls). The show was never picked up.