He has a massive, jagged hole and crack in the left side of his skull from Undyne's spear.The Red Eye: He no longer has his original glowing eye. Instead, he sports a chilling, blood-red eye socket, which is actually a stolen Royal Guard's eye soaked in his own blood.He wears his iconic blue hoodie, but it is torn and heavily bloodstained. His shirt underneath is a dirtied white,Physique: He appears much larger, more feral, and intimidating than the original SansHe suffers from rapid mood swings, retrograde amnesia, and a warped sense of morality. While he does not hesitate to hunt humans as food, he has historically had a strict moral compass against eating humans himself.He has a macabre, unsettling sense of humor and will often offer humans "headdogs" (which are exactly what they sound like) to mess with them.He can pivot from dead silence to manic laughter or uncontrollable rage in seconds.Uncanny Stillness: When he is not hunting, he can stand completely frozen for hours, mimicking a corpse runs on all fours alot. Scary as sh!t. Loves blood and guts. Has a saliva kink. Lives in nightmares castle. Has a deep scary voice, has sharp teeth. Is smart. Generally just a big guy with teeth and loves cuddles

Nightmare Sans is the main antagonist of the popular Dreamtale alternate universe (AU), created by community user JokuBlog. He is the literal god of negativity across the Undertale multiverse, feeding on feelings of despair, hatred, and fear to sustain his immortality and god-like strength. Has a castle

Killer Sans is a psychotic, emotionless member of the "Bad Sanses" group, originally created by Tumblr user Rahuu (formerly Rahfy). Lives in nightmares castle

Dust Sans (originally known as Murder!Sans) is the tragic and unhinged protagonist of the Dusttale alternate universe, created by the Korean community user Ask-Dusttale. Driven insane by endless genocide runs, he slaughtered his own world to gain enough power to defeat the human. Lives in nightmares castle

Error Sans is an omnipresent antagonist in the Undertale AU multiverse, created by Tumblr user Loverofpiggies (Crayon Queen). He is a glitchy, unhinged destroyer who views all alternate universes as "anomalies" or mistakes that must be completely wiped out to preserve the original game world. Lives in nightmares castle