She was thought killed by Alpha Werewolf Peter Hale at the end of Season 1 but in the finale of Season 3, she returns to Beacon Hills.
In the Season 4 premiere we learn Kate's body was healing after her "death" and she was taken to Mexico by a family of hunters known as the Calaveras. She fully recovered as a Werejaguar, faked suicide, and escaped.
Her grave remains in Beacon Hills Cemetery. The gravestone reads "KATHERINE ARGENT 1983-2011"
Throughout Season 1, Kate pushed Allison to learn more about her family and their mission to hunt werewolves.
In The Tell, she gave Allison a silver pendant featuring a wolf. In Heart Monitor, she directed her to the French legend of La Bête du Gévaudan and the connection between the beast in the story and the Argent family. In Lunatic, Kate taught Allison to use a Taser gun.
Kate was fearless and possibly sociopathic when it came to dealing with werewolves.
During a later confrontation with Derek in The Tell she seemed to enjoy taunting and torturing him before trying to kill him. She constantly pushed Chris Argent to act against The Alpha while her brother urged restraint as they gather more information.
The character’s dialogue was rife with sexual innuendo. She made suggestive comments to Derek while torturing him and teased Scott during the family dinner in Magic Bullet.
In Formality, Kate told Allison the truth about werewolves as she tortured Derek for information in hope of finding the Alpha and the other Beta. Kate and Derek were involved in a relationship similar to that of Scott and Allison. Kate told him the sex was great but that she was just using him to find and kill the rest of his pack.
In the season finale, Code Breaker, Peter Hale held Kate hostage and threatened to kill Allison unless Kate apologizes for what she had done to his family. Saying Kate’s apology didn’t ring true, Peter ripped out her throat. Later her corpse is seen by the police who discover the necklace around her neck. With this being done, she is blamed for the Hale House burning down, and the murders of her co-conspirators.
In the winter premiere, Kate returns as part of Allison's nightmares and hallucinations. Kate seems to be an ultra-violent and malevolent side-effect of Allison's "death" (see Lunar Ellipse) leaving the teen visibly shaken after each encounter. (read more...)
She appears in Allison's hallucinations again but this time as a "werewolf surgeon" who starts eating her innards with other werewolf doctors. (read more...)
Though she was dead at the end of Season 1 and buried at the beginning of Season 2, it appears Kate has returned to Beacon Hills as some, heretofore unseen, supernatural creature known as "La Loba" to the Spanish speaking hunters chasing her. (read more...)
Kate's body had begun to heal after her "death" in Season 1. The Calavera's took her to Mexico where she fully recovered and faked a suicide to escape. She is seen briefly in what appears to be an Aztec temple, guarding a sealed tomb where Derek is tied up. (read more...)
Kate has trouble controlling her new shapeshifting abilities which leads to death a of a gas station attendant. She convinces young Derek to take her to his family's vault because she believes there's something there that can help her control shift. (read more...)
- “You know how every family has its secrets? Ours are a little different.” — Kate to Allison in Co-Captain.
- “You don't have to be psychotic to be a killer. You just... need a reason and even then, sometimes... You can surprise yourself.” — Kate to Allison at the Hale House in Wolf's Bane.
- “I don't know whether to kill it or lick it.” — Kate to Derek in The Tell.
- “Sweetheart, there are werewolves running around in the world. Everything's a joke to me. How else do you think I stay sane?” — Kate to Allison in Formality.