Claylossus

Claylossus is a minor antagonist in The Epic Tales of Captain Underpants. He only appears in the episode "The Costly Conundrum of the Calamitous Claylossus."

The Epic Tales of Captain Underpants
In "The Costly Conundrum of the Calamitous Claylossus," Melvin Sneedly built a pottery wheel called the Interclaystation 2000 as a way to dupe Bo into thinking he could trust him and not George Beard and Harold Hutchins. However, the machine malfunctioned and ended up mutating Bo into Claylossus.

Later, he turned George Beard, Harold Hutchins, Captain Underpants, Melvin Sneedly, and the city of Piqua into stop-motion clay.