Arthur Mitchell, aka "The Trinity Killer", is a fictional character in the American crime drama series Dexter, created by Melissa Rosenberg and portrayed by John Lithgow. Serving as the primary antagonist of season 4, the character is a serial killer who murders three individuals every year for the past thirty years in a specific pattern, but has evaded justice all that time.

Arthur Mitchell A.K.A "The Trinity Killer"
"Hello, Dexter Morgan."
Gender: Male
Type: Serial Killer, Villain, Pathological Liar, Sociopath
Age: 60s
Species: Human
Portrayed by: John Lithgow
Status: Deceased
Media of origin: Dexter
First appearance: "Living the Dream" (S4 E1)
Last appearance: "The Getaway" (S4 E12)


Arthur Mitchell is an infamous serial killer known only as "The Trinity Killer" to the general public for his yearly track of murdering three people in a specific pattern, a childless woman in a bathtub with a slit femoral artery, another woman, a mother of two, forced to jump to her death, and finally an alcoholic man beaten to death with a framing hammer. Much like protagonist Dexter Morgan himself, he also has a family, a wife, a son, and a daughter, along with another daughter from a previous marriage with a different last name, Christine. He meets Christine once a year, and seems to treat her as a deadly secret that must be kept from his current family. He becomes a target of Dexter when he strikes again at Miami, and former FBI agent Lundy, though unable to prove his existence, has been tracking him down for 15 years, learning that the span of his crimes go even further than his own investigation. Dexter, however, learning of his familial situation, believes he could learn how to properly run a family by following his example, and ingratiates himself into Arthur Mitchell's life, learning more deadly secrets, including the symbolism in his modus operandi and his true nature.

Why He Rocks

  1. He might quite literally be the best villain in the entire series and the best villain against Dexter, specifically because of how alike they seemingly are, both being serial killers with families who don't know their true natures. He's easily the most complex of them all and provides many interesting themes that are explored in that season.
  2. He is also one of the scariest characters in the entire franchise, considering the mystery surrounding him at first, and how the answer to said mystery only makes him that much more horrifying, he feels more like an urban legend at first, until one realizes the horrifying practicality of his actions.
  3. He has a very intricate backstory that directly influences his MO, namely that he accidentally caused his older sister to slip in the shower, breaking the glass and killing her when it cut her femoral artery, his mother committed suicide, and his father became alcoholic and abusive, leading Arthur to beat him to death.
  4. He's also one of Dexter's most capable villains, leaving no traces of his presence at a given crime scene and nothing for the police to trace him with except for a small trace of his sister's ashes. He also has a higher kill count than Dexter himself gets throughout the show.
  5. He's a very enigmatic character as well, being that the series takes the entire season to reveal his personality and motivations, especially when he suddenly attempts suicide after spreading the last of his sister's ashes, only for Dexter to save him purely for the purpose of being the one to kill him.
  6. He seems to have a rather loving relationship with his family and with the people of his church besides his murder spree, to the point where he helps build homes and by all accounts seems like a perfectly upstanding guy besides the murders, which is what causes Dexter's interest in learning from him.
  7. Many mindblowing twists surrounding him and his actions, including one where it reveals that his sprees aren't in groups of three, but four, since a child goes missing, only for Dexter to learn that this is because he literally kidnaps a child, exploits their pity to the point where they'll let him call them Arthur, then drugs them and puts them in a bag, which he then buries in concrete.
  8. The fact that he's Christine's father comes out of nowhere, especially as he seems appalled by the murder of Agent Lundy and Debra being wounded (and Debra found out Trinity himself didn't wound her before the audience does). What's even more of a shocking twist is that it was, in fact, Christine who murdered Lundy, desperately seeking his approval, which lead to him disowning her since it lead to a legitimate FBI investigation into him.
  9. He often switches between a seemingly upstanding citizen to a psychotic menace on a dime, especially when he's looking for new victims.
  10. John Lithgow successfully breaks type and is absolutely wonderful in the role, making the character legitimately terrifying despite many of his previous roles being a nice guy.
  11. The revelation that he's actually an abuser of his family is absolutely perfect as it shows that he's truly not better at his profession than Dexter is, and leads to Dexter outright regretting not killing him in the first place when he learns that he beats his son, locks up his daughter, and torments his wife psychologically, only giving a perfect facade of a happy family through fear.
  12. His friendship with Dexter turning into a blood feud is one of the highlights not only of the season, but of the entire series, showing how Dexter now has a truly worthy adversary once more, and who would easily destroy everything he has worked for.
  13. He's just as devious as Dexter, to the point where he stalks him back to his office and learns his real name through his nametag, disguising himself as just another ordinary civilian. All this leads to the iconic line, "Hello, Dexter Morgan."
  14. He's pretty much an example of Dexter if he made enough wrong decisions, to the point where he takes all the assets from his already frightened and destitute family to escape Dexter and Miami while also seeking vengeance on him, showing that unlike Dexter, he doesn't value his family.
  15. His death at the end of season 4 is also a highlight, as Dexter had gone to truly insane lengths to take him down and finally succeeded, putting him in a kill room absolutely covered in pictures of his over 120 victims, then playing the song "Venus" by Frankie Avalon before finally killing him, though in his last moments, he simply tells Dexter "It's all over".
  16. Speaking of his final lines, in what is easily the most shocking moment of the entire series, it turns out that he found out Dexter's real address (after going to his old one, which would've threatened Debra if she was there currently) and murdered Rita, who was just going back for something small before her honeymoon, in front of Harrison. This causes Dexter to not only be completely traumatized by this, but also causes him to see a reflection of his own traumatic childhood memory of his mother's murder in the scene with Harrison, causing him to believe that Harrison himself might be on the path to being just like him, easily his worst fear.

Bad Qualities

  1. It can be argued that none of the villains in the rest of the series quite matched up to him, especially in some future seasons.
  2. It seems a little strange that he was an abusive man, yet Dexter thought he saw genuine affection between him and his wife and familial love between him and his kids. This is stranger still as Dexter had been in his house before, yet didn't see the signs he sees in the episode "Hungry Man".


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