Wart is the main antagonist of Super Mario Bros. 2. He is the leader of a gang known as the 8-bits and his major appearance centers around his efforts to conquer Subcon, a land of dreams. Wart's information in the original instruction booklet states, "He is the most mischievous of all in the world of dreams. He created monsters by playing with the dream machine."
And he is voiced by Fred Tatasciore in the English dub and Taiten Kusunoki in normal form and Takashi Nagasako in monster form in the Japanese dub.