Rocksteady was first introduced in the series as Ivan Steranko, a Russian arms dealer and artifact collector with a gold tooth, a diamond right eye, and armed with a pair of brass knuckles (which have a picture of the Soviet hammer and sickle on each), who is an old friend and business partner of the Shredder's. Steranko is known to have Excalibur, the Spear of Destiny, Alexander the Great's armor, tanks, a polar bear hunting trophy, and a taxidermy rhinoceros in his collection and the ability to tell the difference between a fake artifact and a real one.
He first appeared in "Enemy of My Enemy", where he met with Shredder for a weapons deal. Shredder didn't seem to trust him very well, and had the cargo searched just in case Steranko was pulling any tricks. During the Turtles' fight with Shredder, Steranko got knocked out by the weapon that was being sold to the Foot Clan. In "A Chinatown Ghost Story," it was mentioned that Steranko would pay the Purple Dragons through the roof for the Mystic Dagger.
Bebop was later on introduced as Anton Zeck, an African American professional thief in a high-tech Tron-based suit with an energy Mohawk, his dance is almost similar to Michael Jackson's moves, and armed with high-tech gadgets who gave Steranko his diamond right eye in an earlier encounter. He first appeared in "The Legend of the Kuro Kabuto," where he was sent by Steranko to steal Shredder's helmet, the titular Kuro Kabuto. Following his theft, where he left his calling card on a glued-down Rahzar, Zeck ran into the Turtles, who stole the kabuto from him. The Turtles, Rahzar, Fishface, Tiger Claw, and Baxter Stockman fought Zeck over the helmet, but he managed to evade them. When Zeck met up with Steranko in his helicopter, they both discovered that Leonardo swapped the helmet out with dirty diapers at the last minute, to Steranko's rage.