Hero Killer Stain is a character from My Hero Academia who served as the main villain during the second half of Season 2 (Vs Hero Killer arc) and made a brief appearance near the end of Season 6 (Dark Hero arc). A feared sword-wielding vigilante who kills heroes he deems not worthy of the title Stain possesses a quirk that allows him to paralyze someone by licking their blood which can last a while depending on their blood type.