Dark Matter Thieves

Known in Japanese as Ankokutozokudan Dakumata, the Dark Matter Thieves were a company of star-faring raiders who followed the alien king Boros. Their base of operations was a Giant Spaceship of such scale that it blotted out the sky above A-City. Rows of cannons lined its hull, able to launch immense destructive shells, and the whole craft drew its energy from a Power Core; once that core was ruined, the vessel dropped from the air at once.

During the Alien Conquerors Arc, the raiders touched down on Earth and flattened nearly all of A-City, sparing only the Hero Association's headquarters. Melzargard descended first, slaughtering the Sky King and his Skyfolk before locking blades with the A-Class hero Iaian, whom he overwhelmed. As the S-Class fighters rallied, Atomic Samurai carved the shapeshifter apart, and Metal Bat, Bang, and Puri-Puri Prisoner joined the effort. Melzargard's true weakness proved to be small marbles hidden inside each head; crushing them liquefied his forms, and Bang destroyed the final one to finish him.

Aboard the ship, the psychic general Geryuganshoop tried to halt Saitama with hurled boulders, but the hero flicked a lone rock back and split his skull. Saitama then strolled into the throne room and faced Boros, who revealed that a prophecy had driven him to Earth in search of a true match. A careless punch shattered Boros's restraining armor and freed his full power. The two traded devastating blows, Boros firing chest lasers, his Meteoric Burst launching Saitama to the moon, and at last his Collapsing Star Roaring Cannon. Saitama answered with a Serious Punch that overpowered the attack and killed the warlord, who died content at having found a real fight. With its core wrecked, the ship plummeted and was later hauled away by Metal Knight.

Boros held supreme command over the group and perished at Saitama's hands. Beneath him served three generals, the psychic Geryuganshoop, the regenerating Melzargard, and Groribas, all of whom died in the invasion. The Dark Matter Gunner, ranked lieutenant general, manned the ship's artillery until Tatsumaki turned his fired shells back against the vessel. Every named member fell during the attack on A-City.