Killer Sans is part of the bad sanses group, lead by Nightmare. Nightmare being corrupted is advantageous in one way only, Killer is like his right hand. Killer is the Sans from KillerTale, where he went on a massacre after allying with Chara, but in the end Killer ended up killing her. Killer is also a flirt, and reads people easily. He likes a little the childrens and has an obsession with blood. He is a skeleton.