The Clown Killer is an American serial killer who appeared within "Voices Carry". The killer is a famous serial killer who years before the episode was killing people in the LA area and painting clown faces on his victims.

LAPD police officer Harry Trumble was assigned to lead the task force to catch the killer but the original investigation never caught the killer and it was wound down as the killings stopped.

Mark and Steve theorize that the killings didn't stop but the killer moved to different counties all over the world where he carried on killing. In the episode Harry fakes evidence to make it look like the killer is back which the killer takes as an offer to strt killing again.