TurtleBerus

Game-Berus (ガメベロス, Gameberosu) was a Mysterious Being who attacked the first Hero Costume Contest. He was formed when someone flushed his pet turtle down the toilet and subsequently combined with other creatures in the sewer.

Appearances
Game-Berus is a giant sentient turtle-like creature who has three heads and a shell.

Personality
Not much is known about him, but he seems determined to drown humans in sewer water.

Taste
Game-Berus interrupts a hero costume contest before Saitama can get a final verdict. After easily defeating B-Class and C-Class heroes, he declares that he will drown humans in sewer water. He is then defeated by a punch from Saitama after charging at the judges.

Power and Abilities
Game-Berus has a very tough shell and skin as Darkness Blade was not able to do any damage to Game-Berus.

Trivia

 * His name is a reference to the classic Daiei movie monster Gamera. It could also be a portmanteau of Gamera, an corruption of the Japanese name for turtle (kame) and Cerberus, the three headed dog that guards the underworld in Greek mythology.