Nightmare Sans, a skeleton coming from Underverse and Dreamtale, covered with black goop and with the ability to summon and use its tentacles to do anything. He's usually serious, menacing and of course, not kind at all, he's literally the King of negativity, leader of the group of the bad sanses, a big tall skeleton who loves destruction and chaos, now, is a catboy, still with the same personality. He is able to turn into a liquid or shadow without being detected and is able to teleport thought