Jill Wagner as Kate Argent -Werejaguar-
Katherine “Kate” Argent is Allison’s aunt and Chris’s sister, a major antagonist of the series, a werewolf hunter in Season 1, and a werejaguar returning in Season 4. Kate makes her first appearance in episode 4 “Magic Bullet” when she arrives in Beacon Hills to help her family hunt down the Alpha werewolf, and poisons and nearly kills Derek Hale. Like her father Gerard, Kate is bloodthirsty, deadly and cruel, taking pleasure in hurting any werewolf she can. Kate is also very rife with sexual innuendo, using her sexuality to her advantage. Kate was responsible for orchestrating the Hale Fire, murdering Derek Hale’s family six years prior to the series. Despite her cruelty, Kate was close to her niece Allison, whom she gives a necklace which depicts a wolf for her 17th birthday. Kate was the woman whom got chemistry teacher Adrian Harris drunk at a bar and had him reveal to her how to start a fire “and get away with arson” as Harris relayed to Sheriff Stilinski in “Wolf’s Bane”, but he also drew him a necklace he saw Kate wearing that night, the same necklace she gives to Allison. In “Formality”, Kate reveals the supernatural to Allison by showing her a captured Derek. In the past, Kate also had a sexual relationship with a younger Derek Hale simply to betray him and set the Hale House on fire. In the Season 1 finale, Kate convinces Allison to go on the hunt for Derek and Scott after it’s discovered Scott is the other Beta werewolf. She nearly kills Scott, but Chris stops her, confronting her about her involvement in the Hale fire and threatens to shoot her if she doesn’t lower her gun. Kate is later killed by Peter Hale as revenge for the Hale Fire, slashing her throat. After Peter Hale is killed, the necklace is left on Kate’s corpse as evidence for her part in the arson. During Season 3B, Kate appears in visions and nightmares to Allison as a result of the Allison’s Druid sacrifice.
In the Season 3 finale, it is revealed Kate survived Peter’s attempt on her life and is alive. Kate appears and attacks a team of the Calavera hunters in Derek’s loft before shooting Derek himself and abducting him. As Peter had slashed Kate’s throat, its revealed Kate had become supernatural as she transforms into a shapeshifter, a werejaguar. It’s seen in flashbacks, Kate had begun to heal after she was killed by Peter’s claws, she was coming back. The Calaveras came to check if she was really dead and saw that she was transforming instead, so they switched out Kate’s body from the morgue and took her to Mexico where they demanded she take her own life to follow the Hunter’s Code. Instead Kate faked her suicide, and when the hunters inspected her, she killed half a dozen of Araya’s men and escaped. Kate lacked control over her shapeshifting, leaving a trail of bodies behind her. Kate was instinctively drawn to La Iglesia, the ruins of an Aztec temple which worshipped Tezcatlipoca, the Nagual-jaguar god. With her werejaguar status, she found and gained control of a pair of Berserkers giving herself muscle and protection. While in hiding, Kate discovered a cassette someone had anonymously left her; the tape revealed information about the Hale family, specifically their artifact, the Triskelion which was used by the Hales teach their young control on a full moon. Needing to learn control, Kate decided to acquire the Triskelion, which lead to her kidnapping Derek.
In “The Dark Moon”, its revealed Kate had taken Derek to La Iglesia in a tomb. Using the magic of her species’ god, Kate had Derek regressed to the time of his life when she’d seduced him, when he was in love with her, before she’d set the fire. She had him reveal the location of the Hale Vault to her in “117”. She had her Berserkers hold off Scott and his Pack, had Derek take her down to the Vault and found the Triskelion. Peter arrived and amusedly let Kate know the Triskelion didn’t have any magic that helped control, it was just a simple pendant a physical placebo for young Betas to focus on when learning control. Kate faced off against Peter angrily, but smoke bombs were set off by an unseen figure. In the chaos, Kate escaped and called the Berserkers. Kate had been manipulated into accessing the Hale Vault so ‘the Benefactor’ could steal the Hales’ fortune, to use for financing the Dead Pool. Assassins began arriving in Beacon Hills over Season 4 for the money and being worth $12m, Kate begins a manhunt for ‘the Benefactors’ identity, the person she realizes left her the cassette to find, leading her to killing ‘the Orphans’ and confronting Scott and Chris. She tells Chris she needs more time for learning control before eventually confronting him, and when the Berserkers overpower them she spares Chris’ life when one Berserker almost kills him. Kate is later approached by Peter, her would-be murderer; she accepts Peter’s deal, he offers her control over her shapeshifting, she helps him get his money back and help to implement his plan to kill Scott to become an Alpha again. Later on, Kate masters control and attacks Scott and Kira in “A Promise to The Dead”, abducting them and taking them to La Iglesia. Kate had learned from Peter her species, the werejaguar, as “La Loba” ‘the Bone-Woman’ that she has the talent not only to control the Berserkers, but also to create them. Kate sadistically has Scott transformed a Berserker planning to have him fight his own friends having them kill him, or vice versa, following Peter’s plan to have Scott killed. Kate faces off against Scott’s allies along with the Calaveras. She kills multiple hunters, but she is defeated by Derek, in his new full wolf shapeshift, severely mauling her and being shot by Chris with a yellow monkshood laced bullet. Kate appeals to her brother saying her intentions were to have their family’s legacy return to power after it’s decimation, and to have Scott and his Pack killed in revenge for Allison, her niece’s death. Kate escapes.