Jackson Ellis is a minor recurring character in the second half of Season 2 and later, a main character and the tritagonist to Star in Season 3. Nothing is known about him or his past except for the fact that he is an aspiring musician and songwriter who is looking to make something of himself. He's the ex-fiancé of Star Davis, whom he loves very much despite her difficulty opening up about her feelings and was believed to be the father of her child.
His mother comes for a visit towards the end of the first half of season three, and it is awkward for Star to meet her so unexpectedly. Jackson defends Star to his mother, and Star becomes unhappy when she surprisingly buys them a bunch of baby supplies. When Jackson's mother leaves, Star questions the relationship, because of her odd behavior, and Jackson admits that she has bipolar disorder, so he understands her past with an unpredictable parental figure.
During the beginning of Zion, Jackson attempts to propose to Star, but she is served papers, informing her that she cannot sing her single, "There For You", at the upcoming Rhythm and Bells festival. Later on, Star tells Jackson that she likes their relationship the way it is and that she doesn't want to get married. However, just before her performance, Star asks Jackson to propose again, and tells him that she wants to marry him. Star's water breaks right then, and she is forced to deliver the child in the back of an ambulance with Simone and Jackson at her side, along with Noah and Carlotta looking on. However, that Star was told the wrong dates by her doctor of the conception of the child, and that the child, a son, was actually fathered by ex-fling, Noah Brooks. Jackson, at first, seems to bond with the child after the birth, and things start looking up, but leaves when Noah holds the baby for the first time, telling Star he needs a minute. However, he comes to tell Star that he is moving out, and although he doesn't fault her for getting the dates wrong, because the child is not his, he doesn't want to be involved. He is seen leaving his set of keys on the living room couch at Star's new place, and departs.