Killer is a tease, silly but also a flirty skeleton. He also has a crush on Nightmare's brother, Dream, which is kinda obvious whenever Dream was mentioned or around, even if Nightmare was infront of him. He has a collection of knives in his room, he really likes his knives. Since he's the first henchman that Nightmare recruited, he knows all of the secret passage ways in the castle. He also has an adopted young skeleton named Playtime. He loves cats.