Silas King was a drug smuggler who was transporting drugs from Los Angeles to New York City when his van broke down in the Mojave Desert. King spent several days in the desert making his way back to civilization, during which time the exposure to the sun catalyzed his latent mutant abilities. While receiving treatment for sunstroke, he discovered inadvertently that he could discharge this energy as heat blasts.
Taking up the name 'Solarr', King made his way to New York City, where he used his power to rob banks. Over time he established a partnership with Klaw and also joined the Emissaries of Evil, which had been formed by Egghead. He faced off against such superheroes as the Avengers, Captain America, Spider-Man, and the Thing.
Ultimately, Solarr was captured and transferred to the Project PEGASUS energy research center so that his powers could be studied by government scientists. Another captive was Bres, a member of the other-dimensional race known as the Fomor who had magical powers. Detained using electromagnetic shackles that inhibited his powers, a succession of power failures allowed Bres to disable the shackles without anyone's knowledge. He then began to use his powers to secretly take control of the minds of several people at the complex by confronting them with their greatest fears. Among the affected was a guard who suffered a fatal heart attack as a result of his vision. Released by Bres, Solarr happened upon the body of the guard, a man he hated, and he used his powers to incinerate the corpse. Bres's magic animated the corpse, however, and it pursued Solarr, ultimately strangling him.