Race: Artificial Mutant

Gender: Male

Abilities: Immense Strength, Transformation, Weapons; Lion Claws

Level: Demon

Affiliation: House of Evolution

Debut: Chapter 8/Episode 2

Beast King was an artificial mutant created by Dr. Genus of the House of Evolution. Beast King is the leader of Dr. Genus' strike force and second-strongest specimen in the House of Evolution, exceeded only by Carnage Kabuto.

Appearance: Beast King is a large, humanoid lion, with a full mane and tail. In spite of his humanoid, five-digit hands, he still wields sharp claws on his fingers and padded, four-toed feet.

He wears a black shirt, animal furs on his shoulders, and a leopard-skin cloth around his waist, secured by heavy chains and a belt with a lion-head buckle. There are bracelets on both his wrists and ankles, and bracers on both biceps, which he breaks and shatters once enraged.

Personality: Beast King speaks very loudly, roaring and shouting his dialogue constantly. Although only the second-strongest, Beast King revels in his own power, and becomes increasingly frustrated with Saitama's inexplicable strength and absence of fear.

As a leader, he is sadistic and has little regard for his fellow mutants, dismissing his killings of Slugerous and Frog Man as the 'law of the jungle'.