Garou (One Punch Man)

"The popular will win, the hated will lose, it's such a tragedy. Then I won't lose to anyone. I will become the strongest monster ever and change this scenario."

- Garou

Garou is the most dangerous antagonist of the 2015 anime One-Punch Man. was the discipline of Bang, however he was kicked out from his dojo for massacred many of the students, after that event The Hero Association viewed him as an enemy called "Human Monster", He is also the primary antagonist of the Human Monster Saga.

History
When he was a child he was unpopular and can be seen reading a book, one day he played heroes with a popular kid named Tacchan and impersonated the role of the monster, when he was kicked in the face by Tacchan he called the teacher but other children defended Tacchan by saying to her that that's how the game worked.

He later watched an episode of  the Justice Man TV and was extremely irritated by the fact of all the monsters losing to him, he asked to his father when there would be a villain that could defeat Justice Man but he was denied by saying to him that all the monsters in the end will die because they are monsters.

Unable to accept the fact he decided to become the strongest monster and never lose, and to change the scenario.

He is later seen as an adult training with Bang, but when the training was complete he disabled many of the students, including Sour Face, leading Bang to beat him and expelling him from the dojo.

He reappeared talking with Saitama asking him who he was, the latter responded to that he's "The Villain".

After causing great deal of rampage and sent many of heroes crippled and hospitalized, Garou finally met with Saitama... Only to be defeated by him easily. After hearing some lectures from Saitama, doing some quick soul searching and testimonies from a child whom Garou saved from harm during his fight against heroes Garou finally discovered what he had truly wanted to become: a hero. Realizing this Garou fled the scene, leaving everyone but Saitama to wonder where Garou had gone to.