A creature found by miners, Shagrek was originally brought to Earth and sent to the Tokyo Zoo. When local children began to notice that he was learning to talk, biological experts were called in to ascertain if they had mistakenly caged a sentient creature. When his dubious sentience was verified, the people of Japan tried to welcome Shagrek into their lives. However, Shagrek, forever fierce, killed forty people with his disintegrating antenna-beams on his first day of freedom.
Zoltorus intercepted Shagrek and recruited him for the Taurus Gang. As a member of that group he has clashed with the Legion of Super-Heroes multiple times.