Pluton

Pluton (冥界王プル豚, Mēkaiō Puｌuton) was the king of the Underworld.

Appearance
Pluton is a gigantic pig-like creature.

Alien Conquerors Arc
He wrecks havoc in Y-City. However Saitama and Genos quickly come and dispose of him.

Abilities & Powers
Not much was seen of his abilities, due to how quickly Saitama disposed of him, however it can be assumed that he is very powerful because his threat is categorized at a level of "dragon". Pluton however seems to have the ability to suck surrounding debris with his powerful nostrils, assuming that is how he destroyed a large portion of City-Y

Physical Abilities
Immense Strength: Pluton easily destroys a large portion of Y-City.