Killer is a character mentioned in Fallout 4.
Killer is a raider who was killed after his captors failed to succeed in torturing him into allying with Zeller's army. He took pleasure from whatever methods his captors used, he would smile and spit in their faces, so was "put down." His captors reasoned that he probably ran with another raider crew for some time before his captivity.
Killer is mentioned only in Fallout 4.