Subterranean King

The Underground King (地底王 Chitei no Ō) is the king of the Underground People. He led his people from below the surface to conquer the area on it. He was however quickly defeated by Saitama.

Appearance
Like the Underground People, the Underground King has a humanoid appearance, but is about double the size of a regular human being. He is covered with black, armor-like pieces, with lava running in the space between them. He has three, sharp eyes and four arms, all with only three fingers.