Joanna Beth Harvelle is a fictional character on The CW Television Network's drama/horror television series Supernatural portrayed by Alona Tal. Aspiring to be a hunter of supernatural creatures like her parents, she was introduced in the second season in order to explore a mother-daughter relationship in the hunting world. She was ultimately removed from the series by the end of the second season—Kripke admitted the conception of the character was flawed from the beginning—but returned in the fifth and seventh seasons.
Jo first meets Sam and Dean Winchester in the second season episode "Everybody Loves a Clown". The brothers look for her mother Ellen at Harvelle's Roadhouse—a saloon frequented by hunters of supernatural creatures—after she leaves a voice mail message on the phone of their deceased father, John Winchester. Throughout the second season, Jo appears to have romantic feelings for Dean; though he states that he also has feelings for her, he will not act on them for the fear of getting her killed. Wanting to be a hunter like her late father, Bill, to feel connected to him, Jo slips away from the Roadhouse against her mother's wishes to help the brothers on a hunt in "No Exit", but they ultimately have to rescue her from a vengeful spirit. An angry Ellen reveals to her that John's recklessness caused Bill's death, which strains Jo's friendship with Sam and Dean. Jo soon leaves the Roadhouse to live the life of a hunter. When the demon that once possessed Meg Masters possesses Sam in "Born Under a Bad Sign", it finds and captures Jo, planning to threaten her life to force Dean to kill his brother. While holding Jo hostage, the demon plays cruel mind games with her by first telling her that Dean doesn't return her feelings for him and then by telling her that John actually killed Bill to "put him out of his misery" after he incurred fatal wounds, despite Bill's pleas to see his wife and daughter one more time. Dean rescues Jo without harming Sam, but when Jo attempts to join him in capturing the demon, he refuses to allow her to come; he tells Jo he will call her, but as he leaves, she mutters, "No, you won't."
In the fifth season episode "Good God, Y'All!", Jo reappears with her mother Ellen in a small Colorado town called River Pass. They plan to help Rufus, a demon hunter and one of Bobby's friends, kill the demons that have laid siege to the town. However, Jo and Ellen are separated in the chaos. Jo later finds and joins up with Rufus and other townspeople. Eventually, they attack Sam and Ellen, both of them appearing to be possessed by demons. Jo joins in with Rufus to torture the supposed "demon" out of a captured Sam with holy water and salt, but becomes doubtful when no demonic effects are present on Sam. Dean and Ellen arrive and, after a brief struggle, convince Jo and Rufus that War, one of the Four Horsemen of the Apocalypse, is responsible for making all the townspeople turn against each other by thinking that both sides are demons. Jo and Ellen team up with the Winchesters again in "Abandon All Hope...", where they help the brothers reacquire the Colt — a mystical gun rumored to be capable of killing anything — in order to kill Lucifer. Upon tracking his location to an abandoned town, they are confronted by Meg, accompanied by a pack of hellhounds. The group of hunters flee, but Jo is injured when saving Dean from the hellhounds. Knowing that her wounds are fatal and that Lucifer must be stopped, Jo convinces the others to build a bomb and to use her as bait for a trap. Ellen stays behind and opens the front doors while the Winchesters escape onto the roof. After Jo dies in her arms, Ellen blows up the building, killing the hellhounds and herself in the process.
Jo is mentioned but not seen in the sixth season episode "My Heart Will Go On", in which she is temporarily restored to life as a result of the angel Balthazar saving the Titanic from its destined sinking. She makes an on-screen return in the seventh season episode "Defending Your Life" as a ghostly witness called by the Egyptian god Osiris when he is judging Dean's guilt. Jo's ghost instead testifies that Dean was not responsible for her fate. Osiris declares him guilty anyway and forces her to try to kill Dean, but she is able to take her leave in peace when Sam kills Osiris and thereby frees her from the god's control. Supernatural executive producer Robert Singer confirmed that the apparition was Jo's ghost and not an illusion created by Osiris.