- Shredder - Steranko and Shredder have been old friends and business partners in the mafia, but Shredder didn't seen to trust him that much. Little does Shredder know that Steranko was the one who hired Zeck to steal his helmet and hunted Karai. As punishment, Shredder has Steranko employed into his service.
- Anton Zeck / Bebop - Steranko employed Zeck after the thief shot his right eye out in an earlier encounter. To give him the opportunity to make up for his mistake, Steranko hired him to steal Shredder's helmet in The Legend of the Kuro Kabuto. In Serpent Hunt, they planned to hunt Karai and used her as a bargaining chip for the Shredder so they can leave the city.
- Rahzar - Steranko fought Rahzar during the deal with Shredder by using a restrained Karai as a shield. Afterwards, Rahzar kicks him into a mutagen vat filled with rhino DNA, causing Steranko's mutation.
- Tiger Claw - Rocksteady fears Tiger Claw very much. In Attack of the Mega Shredder, he and Bebop are being educated in pain by Tiger Claw for letting Leo and Mikey sabotaged the mutagen.
- Leonardo - During the fight on the Coney Comet roller-coaster, Rocksteady threatened to hurt Mikey if Leo doesn't give the retromutagen to him.
- Raphael - Steranko fought Raph while hunting Karai and punches him in the forehead with his knuckledusters, later capturing him at the theatre, making him Raph's new archenemy. In The Noxious Avenger, Rocksteady became annoyed by Raph, despite thinking it was a grocery list. In Attack of the Mega Shredder, Rocksteady was insulted by Raph, despite saying rhinos have terrible aim and he also injures his leg. In Darkest Plight, he fought Raph and Casey with Bebop who are trying to rescue Splinter.
- Michelangelo - Rocksteady believes that Mikey isn't so bad at names, because when Mikey gave him his mutant name, he kinda liked it.
Casey Jones - Rocksteady fought Casey outside a theatre and was indestructible against his hockey puck bombs. As a result, Casey and Raph are captured.
Karai - Steranko hunted Karai so he and Zeck could use her as a bargaing chip for a deal with Shredder.
Muckman - After learning of Muckman on TV, Rocksteady employed him into his and Bebop's service to find the Reagent-X to make the mind control serum, but the plan was foiled when Muckman betrayed them to the Turtles.