|“||I was still in pigtails when my dad died, but I remember him coming home from a hunt. He'd burst through that door like—like Steve McQueen or something. And he'd sweep me up in his arms, and I'd breathe in that old leather jacket of his. And my mom, who was sour and pissed from the minute he left, she started smiling again. And we were... we were a family. You wanna know why I want to do the job? For him. It's my way of being close to him. Now tell me what's wrong with that.||”|
— Jo Harvelle on hunting
in No Exit
Joanna Beth Harvelle, nicknamed Jo, was the daughter of hunters Bill and Ellen Harvelle. After her father's death, Jo became a hunter in his memory. Although she fulfilled her dream, she died while saving Dean and Sam from a hellhound sent upon them by the demon, Meg Masters.
Jo was 5'4" and slim. She had brown eyes and long wavy blonde hair which appeared to have darkened slightly between the second season and the fifth season. As a ghost in Defending Your Life, her skin was visibly paler than it'd been in life. She usually wore jeans combined with short-sleeved or sleeveless tops, such as a tank top in her first appearance or the T-shirts she wore in Abandon All Hope.... By the fifth season, she had started wearing a light green jacket while hunting. In Defending Your Life, she wore the outfit she'd died in: her green jacket over a gray shirt and jeans and boots.
When Jo was first introduced, she acted confident yet reserved when subduing Dean Winchester. She gradually revealed more of her personality to the brothers as they got to know each other, revealing her enthusiasm, a sarcastic sense of humor, and an intelligence that surprised Dean when he realized that she had put together a comprehensive file on a case. However, after she learned that their father had gotten hers killed, she became closed-off once more. She hardened up more so from hunting.
Initially Jo held "half-baked" idealized notions about hunting. She wanted to be a hunter because it was her way of feeling close to her father; she disliked attending school because she felt it was a waste of time and believed others viewed her as "the freak with the knife collection." When Sam asked her if hunting was as glamorous as she expected near the end of "No Exit", she admitted it was frightening but pointed out that it was worth it because the person they'd saved would live because of them.
Jo was strong-willed once she set her mind to something. She was also quick to call people out on their behavior, such as Dean on his perceived chauvinism and her fellow hunters when they refused to admit that she could not be saved. Even when she got scared, Jo was quite brave. She briefly broke down into tears when trapped to die in No Exit but then quickly pulled herself together in order to comfort fellow abductee Teresa. She was reckless and willing to risk her life in order to get the job done.
Jo's emotions sometimes led her to be foolish or irrational. Her grief over Bill instilled in her the desire to become a hunter, and she became so upset once she learned of John's association with his death that she unjustly held a grudge against Sam and Dean for it. Her crush on Dean was strong enough that she still had feelings for him (as Meg noted) despite her anger at him over her father's death.
Jo was born to Bill and Ellen Harvelle on April 7, 1985 as the couple's only child. Because she lived at the Roadhouse, Jo grew up around hunters, including John Winchester and Bobby Singer, whom she and her parents regarded as family. She called the hunters she knew "uncle", such as Uncle Caleb and Uncle Shawn.
On Jo's eighth birthday, Bill gave her a bow-and-arrow set and taught her how to use it, while Ellen gave her a diary to write in, which she later turned into a hunter's journal.
On May 16, 1995, Jo learned that her father had died on a hunt. She was devastated by his death. She also began wanting to become a hunter herself, to feel close to her father and be a "hero" like her father and save people. However, Ellen's protectiveness prevented her from fulfilling her dream. After Jo got into a fight with a bully who was bothering her at school, Shawn started training her in hand-to-hand combat.
Jo met Gordon Walker when she was twelve years old. They became friends, though she had a crush on him. When she was 16, he manipulated her into accompanying him on a hunt and unwittingly acting as bait for a rawhead. She became frightened and fled, running right into her mother, who had figured out what they were doing and tracked them down. Furious, Ellen forbade them from meeting again but her daughter secretly kept in contact with him online. Jo also befriended Ash, who started living at the Roadhouse.
Jo tried to attend college per her mother's wishes. However, Jo felt she never fit in and dropped out, returning to the Roadhouse. When Jo was nineteen years old, she dated a hunter named Rick. He stopped contacting her in the middle of a hunt, which worried her; whether he was killed or merely wanted to end their relationship was not revealed.
In Everybody Loves a Clown, Jo first met Sam and Dean Winchester. Thinking they were intruders, she held Dean at gunpoint while Ellen apprehended Sam; Dean disarmed Jo, but she punched him in the face and took her gun back. Despite this rocky start, they became friends when Ellen realized they were John's sons and the Winchester brothers paid irregular visits to the Roadhouse.
In No Exit, eager to go on her first hunt, Jo complied research on a case in which six young blonde women vanished from the same apartment building in Philadelphia, Pennsylvania for over eighty years. To prepare for the trip, she earned money from bets.
Ellen refused to let Jo go out of fear that she would be killed, and instead passed the case onto Sam and Dean. Jo, however, enlisted Ash's help in creating a paper trail to convince her mother that she was going to Las Vegas, Nevada while she actually went to Philadelphia to investigate on her own. In the guise of a potential buyer, Jo encountered Sam and Dean at the apartment and later convinced them to let her join them on the case.
When the group found no reports of a violent death that could explain a spirit's presence, they split up to search for EMF, with Dean accompanying Jo to watch over her and urging her to pursue a normal life rather than that of a hunter's. She felt the spirit try to grab her and they found EMF and a bloody clump of hair from one of its victims within a wall vent. Jo did not sleep that night as she was too busy reviewing information about the case. The next morning, she bonded with Dean; his attempt to give her one of his knives to replace the one she was carrying (which had belonged to Bill) led to them talking about their fathers and her revealing her reason for hunting to him. She, Dean, and Sam learned that Teresa Ellis, another blonde woman, had gone missing the night before.
Jo realized that criminals from a prison that was later destroyed had been executed on the grounds that the apartment building was built over. With Ash's help, Sam identified the ghost as America's first serial killer, Henry H Holmes, whose remains had been buried and encased in concrete. The group split up again to try to locate Teresa inside the building's walls. While separated from Dean, Jo was abducted by Holmes and imprisoned in a torture chamber in an abandoned sewer system beneath the apartment's foundation. Holmes grabbed Jo by the hair and ripped off part of her hair. She attempted to break out of the chamber and slashed Holmes' hand with her father's knife when he groped her.
Sam and Dean arrived and rescued Teresa. Jo agreed to be used as bait to lure Holmes out as their only viable plan. When he manifested to attack her, she escaped, and the brothers trapped him within a ring of salt and sealed him into the chamber using cement. Having learned that her daughter went against her wishes to hunt in Philadelphia from Ash, a very angry Ellen took Jo back to the Roadhouse. When Jo tried to defuse her mother's temper, she realized that there was something Ellen wasn't telling her and she learned that John Winchester had been Bill's partner for his last hunt: John caused his death when he exposed them to the creature they were hunting. Hurt and upset, Jo confronted Dean and Sam with this knowledge, blaming John, and by proxy, them, for her father's death.
Jo left home weeks before Hunted in order to become a hunter when Ellen continued to refuse to allow her to do it, proclaiming that Jo would not be allowed to be one as long as she lived under her roof. She still kept in touch with her mother by sending her postcards.
In Born Under a Bad Sign, the demon Meg, while possessing Sam, tracked Jo down to the Sandpiper, a bar that she worked at in Duluth, Minnesota. She did not initially realize Sam was possessed and was uncomfortable about his presence from their last encounter and because of the strange shift in his personality: he mocked her about her crush on Dean and tried to seduce her. He overpowered her and knocked her out when she rejected him. Jo woke up tied to a post. Meg forced her to recount Bill's death, but claimed that what Ellen told her was not the truth: what really happened, Meg taunted, was that Bill survived with horrific injuries and John shot him dead to end his suffering.Dean traced Meg's location via his cell phone. However, he refused to kill his brother to protect Jo and instead revealed that Sam was possessed. When Meg fled, Dean untied a shocked Jo and went after him. Jo saved Dean's life by bandaging his wound after Meg shot him and left him to drown, having found him using his cell phone ringtone. Remembering what Meg had said, she asked Dean if demons occasionally tell the truth as well as lies but did not reveal what she'd been told. She wanted to help him pursue Meg, but he refused.
In All Hell Breaks Loose - Part 1, Jo had already left the Roadhouse months before demons burned it down, killing everyone inside, including Ash and many hunters. Ellen survived on simple good luck, having been out buying pretzels at the time. At some point, Jo and Ellen reunited and became hunting partners.
After Lucifer's release from Hell, the Harvelles went to River Pass, Colorado to help Rufus Turner fend off an apparent demonic siege, but got separated in the chaos, with Jo joining up with Rufus and some other townspeople.
Jo and Rufus fought Ellen and Sam, both sides perceiving the other as being possessed by demons due to the presence of War, one of the Horsemen of the Apocalypse. Jo and Rufus captured Sam to exorcise him but were confused when all of their anti-demonic measures failed to work on him. War, disguised as one of the townspeople on Jo and Rufus' side, made it appear as though Sam had attacked him and said more demons were coming. When Rufus set pipe-bombs to slow down the "demons", Jo worried about her mother's safety, but he reassured her that he would help her save Ellen from her "possession".
After a brief struggle, Ellen and Dean managed to convince Jo and Rufus that all of the supposed possessions were hallucinations created by War to pit them against each other. Jo helped to prevent the townspeople from slaughtering each other until War's spell ended.
That night, the group of hunters spent the night at Bobby's house. Jo drank a beer and watched on in amusement as Ellen challenged Castiel to shots and lost. When Dean tried to seduce Jo, she turned him down with a laugh. She then joined the group photo and became unsettled by Castiel's grim prediction that they would likely die the next day.
At Carthage, Missouri, the Harvelles, the Winchesters, and Castiel split into two groups, with Jo looking for survivors in the abandoned town with Ellen and Castiel, who left to investigate after detecting a large gathering of reapers and instead got captured by Lucifer. Jo and Ellen confirmed that all the buildings in town were empty before re-joining Sam and Dean.
Meg arrived to capture the Winchesters and set a pack of hellhounds upon the group of hunters. Jo saved Dean's life from a hellhound when she saw him knocked to the ground, but it cost her hers; she was injured to the point that she could not walk and bleeding heavily.
Dean carried Jo into a nearby convenience store while Sam and Ellen fended off the hellhounds. They salted the entrances to the store and bandaged Jo's wounds as best they could, but she interrupted when they tried to figure out how to save her and pointed out the reality of the situation: she was dying. In desperation, she suggested that they construct bombs out of iron and salt and escape, leaving her alone to detonate the bombs and kill the hellhounds.
The other hunters reluctantly assembled the bombs and gave Jo the trigger. Although the brothers left the building via fire escape, Ellen planned to stay behind and die with her, saying that someone needed to let the dogs in and that she would not let Jo die alone. Jo was distraught by the idea of her mother dying as well, but tearfully accepted her decision.
Tragically, Jo died in her mother's arms before she could activate the explosions, not even able to finish saying, "I love you," back to Ellen, who blew up the store, killing both herself and the dogs.
As the Harvelles had been close friends, Sam, Dean, and Bobby grieved over their deaths. Dean wanted to avenge Jo and her mother by killing Meg in Caged Heat, but the demon fled before he could.
When Sam and Dean's souls end up in Heaven in Dark Side of the Moon, they asked Ash about the Harvelles. Ash, however, was surprised to learn that they were dead. Whether this means that Jo and Ellen's souls (as well as those of John and Mary Winchester) are not in Heaven or merely that Ash had yet to encounter them remains to be seen.
In My Heart Will Go On, the alternate timeline created by Balthazar, the Harvelles were still alive. Jo hunted with "her own crew" and occasionally with her mother. Like Sam and Dean, she was investigating the freak deaths caused by one of the sisters of Fate, Atropos. Castiel was forced to reset the original timeline when the Winchesters were threatened by Atropos, resulting in Jo and Ellen having died back in Carthage once again.
- "You carry all kinds of crap you don't have to Dean. Kind of gets clearer when you're dead." — Jo, to Dean
In Defending Your Life, when Dean Winchester was put on trial for his guilt by Osiris, Jo's ghost was summoned as a witness. Although Osiris failed to make her testify against Dean, Dean was pronounced guilty and she was compelled against her will to try to kill him in a manner reflecting her death: she turned the gas on the stove on, broke the window to blow away the ring of salt he was protecting himself with, and took his lighter to ignite the gas and kill Dean in an explosion. Sam Winchester temporarily incapacitated Osiris, however, freeing Jo from his control and causing her to vanish, but not before she tenderly touched his face.
- Season 5
- Supernatural series creator Eric Kripke initially described Jo as an "innocent girl who wanted to be a hunter" and who tends to look before she leaps; she is also "enthusiastic" and very "girl-next-door in her approach" to hunting the supernatural. However, Jo grows throughout the season as she rebels against her mother by running away to be a hunter, which Kripke felt made her harder and tougher. Regarding her character's capture by a vengeful spirit in No Exit, actress Alona Tal felt that Jo was a "badass" who handled the situation well. Tal commented, "She fought and risked her life and stayed there as bait. It took a lot of guts." 
- Actress Alona Tal noted that Jo matures during her hiatus. Having found out the hard way that "banter doesn't always work", she becomes quieter and "not as mouthy". The character "called the shots" in her final appearance, and was the "bigger person" by forcing everyone to accept the reality of the situation. After years of hunting together, the relationship between Jo and Ellen also develops; Tal came to view them more as equals rather than daughter and mother. Although Jo's feelings for Dean remain the same, Tal liked the fact that she does not easily give in to Dean's advances in Abandon All Hope.... She believed that Jo resists her urge to "go crazy [with him]" due to the dire circumstances, which "gave it a little more meaning". 
- In early drafts of the Everybody Loves a Clown script, Jo was named "Alex" and was already a hunter. The Rakshasa case was hers before Ellen reassigned it to Sam and Dean.
- Although Jo was created to be a major recurring character, she was widely disliked by fans for most of her appearances due to a perceived immaturity. As a result, she was soon written off the show. The character development she displayed in the fifth season increased her popularity dramatically.
- Her first name ("Joanna") means "grace" and could be a reference to Joan of Arc, a French folk heroine who was famous as a female warrior who was executed and later declared a martyr. Jo's middle name ("Beth") is a nickname for "Elizabeth", which means "My God is an oath". Her surname ("Harvelle") is a female name meaning "warrior".
- Jo's Blog documented her life, her desire to become a hunter, her first relationship with Rick, and her tutelage by Gordon. It was part of the Hunter's Blog section on the Official Website which was first made accessible with the release of the Season 1 DVD. The content has been edited and changed significantly. Luckily, some fans have recorded the blog entries at various stages.
- According to the original version of Jo's Blog, she knew John as early as 1994 and called him "Uncle John".
- Jo's email address was "email@example.com".
- All the men she was known to have feelings for (Gordon Walker, Rick, and Dean) were hunters.
- Jo was a fan of REO Speedwagon; she defended her musical tastes to an amused Dean by saying that "Kevin Cronin sings it from the heart."
- She carried one of her father's knives, which was pure-iron and had his initials engraved on it. She used it on a ghost in No Exit.
- Meg's account of how Bill died was similar to how Jo died: both Harvelles were fatally wounded by creatures from Hell as a result of their partnership with a Winchester. Meg also claimed that Bill was "holding his guts in his hands" while Jo said "my guts are being held in by an ace bandage."