Rocksteady (2012 TMNT)

Steranko was introduced in the episode Enemy Of My Enemy. He is a Russian arms dealer with ties to Shredder and The Foot. He was mutated into the classic TMNT character Rocksteady.

Appearance
As Steranko: Steranko wears a black suit with shoulder pads with spikes on it, a black undershirt, a red tie, an Ushanka with a yellow star on it, and on his fists two golden knuckle dusters, with a hammer on one and a sickle on the other. He is blonde-haired and has a diamond eye, as well as several scars on his face.

History
Appears to be close to Shredder, given an offhanded mention that they're "old friends". He is first seen talking to Shredder, albeit left unnamed, about a weapons deal. He is presumably knocked unconscious by the weapon that was meant to incapacitate Shredder.

In The Legend of the Kuro Kabuto, he was revealed to have some past with Anton Zeck, who (allegedly, accidentally), is the one who shot out Steranko's eye. Steranko, an ancient artifacts collector, hires Zecks in to steal the Kuro Kabuto from Shredder.

Among Steranko's ancient armory are the Spear of Destiny and Excalibur.

Personality
Steranko is a a large, muscular man with a thick Russian accent. He describes himself and the Shredder as "old friends". His most distinguishing feature is that he seems to be missing his right eye, having replaced it with a diamond studded prosthetic.