Many years ago, his spaceship crash landed on Earth. It imbedded itself on the bottom of the sea and he was unable to free it. When he searched for help the humans feared and attacked him so he used his Ray Gun to turn the attackers to stone.
Many years later he asked Namor for help and in return he had to turn the Avengers to stone while at a press conference. Captain America was not turned to stone, and with the help of Rick Jones, he tracked down the alien. Once he had confronted the alien he offered the Avengers help in return for the alien to restore them back from being stone. Once restored the Avengers took him to his spaceship at the bottom of the sea and Thor helped bring the ship up far enough for him to make repairs. After his repairs were done he departed Earth in what seemed like an underwater earthquake which separated the Avengers from the foe they were fighting at that point - Namor and his forces. Namor believed that the Avengers had been destroyed and left.
Starhammer possesses standard D'bari strength without armor. Like all D'bari, he is extremely long-lived (measuring his life span in centuries rather than years). He can reproduce sexually and asexually by budding, but the latter only every thousand years.
Starhammer's armor magnifies his strength, lifting at least 10 tons. The Starhammer armnr has psionic shields and is immune to most physical attacks. It can presumably be used in outer space due to its sealed environment.
Starhammer employs a variety of weapons, including an energy club and an incineration gun. He previously used the Petrifactor, which fired a blast that turned its target to stone for 100 Earth hours, as well as returning petrified targets to normal with a second exposure. Overloading the gun's power pack caused a single energy burst that affected everything within 100,000 miles.