Tomura Shigaraki

Quirk: Decay

Leader of the League of Villains and protégé of All For One. He was raised by his master, All For One, with the goal of killing All Might, and ultimately destroying the society he represents.

Tomura is a very twisted, malevolent, and maliciously warped young man, who is considered to be the polar opposite of Izuku Midoriya. He doesn't care for his or almost anyone else's life, having no qualms about performing evil deeds like murdering innocent people. Tomura was initially perceived to be a "man-child": arrogant, selfish, dependent, and demanding, becoming angry if things didn't go his way and likening reality to some sort of video game. Unlike his mentor, Tomura lacked subtlety, preferring to eliminate problems through force. Much like a child, Tomura seemed unable to cope with his own feelings, instead lashing out and abusing both others or himself, tearing at his own neck when he becomes frustrated.

Initially, Tomura seemingly caused destruction just for the sake of it and felt directionless about the League's path forward after Stain's arrest. It would take a fateful meeting with Izuku in a mall for him to develop an epiphany and become aware of his true convictions: to crumble hero society through All Might's death.

Tomura's Quirk allows him to disintegrate whatever he touches with all five fingers. It will take effect whether the target is organic or not. The disintegration spreads quickly and will spread through the victim's whole body if they don't amputate the decaying body part. His Quirk can even spread beyond what he's touching, allowing him to disintegrate large groups of enemies instantly.

(Source: My Hero Academia Wiki)