A member of the Legion of Super-Heroes who can increase the mass of objects.
He is in reality Thom Kallor, from 30th century Xanthu, who was born on a space station where his parents conducted research on the light emitted from celestial stars. This starlight gives Thom the ability to draw mass from the stars and transfer it into any object - making it super-heavy (Adv No. 365, Feb 1968: "Origins and Powers of the Legion of Super-Heroes!").
In March 1961, Thom briefly possesses additional "pseudo-Kryptonian" powers nearly identical to Superboy's, after he is exposed to the radioactive emissions of a comet's tail. These powers differ only slightly from Superboy's, with Thom possessing electrical and infrared visions instead of heat vision, and a form of X-ray vision that is blocked by copper rather than lead. During this time, Thom has a Lana Lang-like girlfriend named Zynthia (Adv No. 282, Mar 1961: "Lana Lang and the Legion of Super-Heroes!").
In March 1966, Thom is suspended from the Legion for killing in self-defense (Adv No. 342, Mar 1966: "The Legionnaire Who Killed!"), but is later re-admitted.