Mikall and Lyysa Jurndall were lovers, and two lone pacifists among an warrior alien race intent on the conquest of other worlds. When Mikall's people attempted to invade the Earth in the 1970's, Mikaal and Lyysa rebelled, resulting in Lyssa's death.
Mikall fled to Earth, where he covertly defended the Earth against his own people, using a sonic crystal which gave the wielder the ability to fly and create rays of focused light energy. He did so until the invasions stopped. He then used his powers to fight crime, his alien apperance causing him to be dubbed "Starman", after the the then-popular David Bowie song.
Relocating to Opal City (because he heard that was the home of another Starman), Mikaal was drawn into a hollow, aimless life of drugs and partying. He was confronted at a disco by Komak; a member of his race, who said they were the last of their kind. His memory erased by his drug use, Mikaal barely remembed his past history. It mattered not to Komak, who still challenged Mikaal to a battle to the death.
Mikaal won that battle, but was abducted later that night, his whereabouts a mystery until he was discovered by Jack Knight in a circus freak show. His memory and ability to communicate were gone, and until recently he remained in Ted Knight's care.
Since that time, Mikhal has regained his ability to speak and even more recently regained memories of his race's history. He also regained the ability to use the powers of the sonic crystal, which is now embedded in his chest.