Killer Sans

Gaster Blasters' bones and teeth are sharpened;
instead of blood when wounded, he bleeds a black substance;
Possesses a "True Knife" that deals 99 damage; has high health thanks to the determination gained from Chara.

He has a red soul in the shape of a target and black liquid flowing from his eyes (symbolizing hatred). In an alternate version, he wears a hoodie with an inverted color scheme (from pale blue to classic), shorts with black stripes, and sneakers.

The character has four stages of state:

First stage: Killer looks like a normal Sans, you can communicate with him normally.

Stage Two: A classic killer who should not be trusted.

The third stage is "mad mode", where Killer causes damage to everything in his path.

Stage four: the most dangerous, little is known about it.

He has a clouded mind and craves to kill or hurt others because it gives him pleasure. He is selfish, distrustful of others, and acts only in his own interests. Occasionally, a tiny spot appears in his right eye socket—an attempt by the "classic" Sans to break free. At such moments, Killer experiences breakdowns and begins to experience emotions, remembering the pain he has caused. Papyrus's shadow also sometimes appears to him, intensifying his feelings of guilt.