2. Arthur Mitchell - The Trinity Killer - Season 4
Though the Trinity Killer takes the top spot on most "Best Dexter Foes" lists, he's missing one key aspect that would have placed him as my number 1. However, more on that in a minute. Arthur Mitchell, played wonderfully by John Lithgow (who received a Golden Globe and Emmy for the role), is the main antagonist in season 4 and has had one of the biggest effects on Dexter as a character: he kills Dexter's wife, Rita. Mitchell had been killing people using the same pattern for over 30 years, going unnoticed to all except for Agent Lundy, now retired. His cycle contained three murders: He would cut a woman's leg in a bathtub, letting her bleed to death. Then, he would force a mother to jump from a parking garage to her death. Finally, he would lure a man down a dark alleyway and bludgeon him to death. He had a fourth murder in each cycle that Lundy didn't know about, which was to take an innocent child and bury him alive in cement (using his charitable house-building project as a cover). Dexter was amazed by Trinity, and looked up to him as an idol. He had lived a seemingly normal life for decades, had a loving family, and was able to carry out his murders without being caught. Dexter slowly forces his way into Trinity's life, trying to find ways to learn from him and live a similar lifestyle. Little did Dexter know that Trinity was actually an incredibly damaged man, whose family lived in constant fear of him. The Thanksgiving meal that Dexter shares with the family remains one of the most brilliant, intense scenes in the entire series. But, of course, Dexter's idolization of Trinity doesn't come without a cost. Dexter had, on several occasions, the chance to kill Trinity, but chose not to out of selfish reasons. Once Trinity discovered who Dexter was, he committed his final murder. After Dexter finally killed Trinity and dumped his body into the ocean, he came home to find his wife Rita dead in a bathtub full of blood, her leg cut open, the final victim of the Trinity killer. And Trinity left Dexter's son Harrison sitting in a pool of his mother's blood, an image that reflects Dexter's own beginning.
Memorable Moment: Murdering Rita and leaving Harrison in a pool of her blood, while giving Dexter no hint of the deed when on his table.