Dexter Morgan is the main character and narrator of the hit television series Dexter on HBO. He is a vigilante, a father, and a hard working blood spatter expert at Miami Metro Police Department.
Quick Bio from Wikipedia:
Dexter was born on February 1, 1971. At the story’s outset, Dexter knows very little about his life prior to being adopted by Harry Morgan (a Miami detective), and his wife Doris. Harry only tells Dexter that his parents were killed in a car accident. When Dexter is seven, Harry discovers that the boy has been killing neighborhood pets. Harry realizes that Dexter is a sociopath with an innate need to kill, and decided to channel the boy’s homicidal urges in a “positive” direction by teaching him to be a careful, meticulous killer of people who “deserve it”—murderers who had escaped justice. Doris died when Dexter was 16, and Harry died when Dexter was 20.