The Trinity Killer was the Main Antagonist of Season 4 in Dexter, who is believed to be a Serial Killer that kills 3 victims for each kill cycle he partakes in (a young woman in a bathtub, a middle-aged mother whom he coerces into suicide and a middle-aged father whom he bludgeons to death). Later on, however, it is shown that he actually kills in cycles of 4, the first victim being a 10-year old boy who is buried alive in cement whilst unconscious, 5 days before a woman is killed in a bathtub. He has been killing for about 30 years all over America and probably has the highest kill-count of any character in the series.