Clear Note
Clear Note is the main mamodo antagonist of the King Festival arc of Zatch Bell!. After Gash defeated his brother, Zeon, he gave Gash a letter that revealed that there was an evil power even greater than his still out there. Shortly after the King Festival began, Gash was confronted by Ashuron, one of the finalists, who revealed that this evil was Clear Note, one of the remaining mamodo. Clear compares himself to a nuclear bomb and wishes to erase both the Mamodo World and the Earth World. His main power is Annihilation. (Source: ZatchBell Wiki and Wikipedia)