The Nuka-Killer is a character mentioned in Fallout 4.
The Nuka-Killer was a pre-War serial killer, it is unknown exactly how many victims he or she had but it is known that he had at least three victims. What is known comes from his victims Gonzalez, Yavits, and Wright, and the details on the Nahant Sherrif's Department, East Boston police station, and Coast Guard Pier evidence terminals. The Nuka Killer apparently got his name because he would stick bottlecaps in his victims eye sockets, and his victims clothes would apparently be waterlogged.
The Nuka-Killer is only mentioned in Fallout 4.