Awhile back, maybe two or three years ago, I had the thought that the only thing I hadn't seen done with serial killer plots is to have a serial killer who only kills other serial killers. He would get off on the idea that he's superior to these ultimate predators if he can find and kill them. Ordinary victims would be beneath this uber serial killer. I would have written it except that I had grave reservations about living with that kind of material long enough to finish a novel, and with adding to the glorification of serial killers that our culture has been flooded with. I'd prefer to uplift rather than depress the psyche.
Well, someone else did it, though it seems their serial killer just hunts other killers, not necessarily serial killers.
See Dexter on CBS February 17, formerly seen on Showtime and available through iTunes. Michael C. Hall of Six Feet Under is in the starring role.