Dexter (2006)

Dexter follows Dexter Morgan, a forensic blood-spatter analyst for the Miami Metro Police Department who leads a secret life as a vigilante serial killer. Raised by his adoptive father, Harry, to channel his homicidal urges for "good," Dexter only targets other murderers. Throughout the series, Dexter struggles to maintain his double life, form relationships, and reconcile his need to kill with his desire to be a good person. The show blends dark humor, psychological depth, and moral ambiguity.