Monokuma

Monokuma is the main antagonist of the series. A strange, remote-controlled teddy bear who proclaims himself to be the principal of Hope's Peak Academy and initiates a life of mutual killing amongst the students. He has various copies of himself throughout the Academy and will punish, ie. kill, anyone that attempts to attack him or otherwise break the academy's rules. Much like his name, he has a monochrome appearance, with one half looking like a cute white bear and the other half looking like a sadistic black bear. Just who the mastermind controlling him is, along with his motives for bringing the students together, serve as some of the game's main mysteries.

Monokuma is known as the symbol of Junko Enoshima, the Ultimate Despair and the true main antagonist of the series. Junko was the mastermind behind Monokuma throughout the events of Killing School Life and Killing School Trip.
(Source: Wikipedia)