Iron Cross

Helmut Gruler, better known as Iron Cross, was a soldier of HYDRA during World War II.

Captain America: Super Soldier
Once Arnim Zola was free to begin tinkering with the power of the reality-warping Cosmic Cube to create new weapons for HYDRA, he began to think on how to improve the standard tank. Attempting to rectify the mobility problems of the heavy vehicles, he envisioned a massive mechanical suit to serve a similar purpose. Because the recoil of standard ballistic weaponry would throw off the accuracy of his new mech suit, Arnim Zola created a massive sonic cannon, and mounted it on the suit's shoulder, allowing the Man-Propelled Tank to stun and cause panic in the ranks of the enemy, before closing in with a custom-designed ballistic-shield to engage and crush the debilitated foes in close range. After selecting a pilot, the massive HYDRA enforcer, Iron Cross was born.

Arriving at Castle Zemo at an unknown point, Iron Cross surprised Captain America by ambushing the battle-weary and bruised super soldier after his battle with Baron Wolfgang von Strucker. While Iron Cross' attack would have killed a normal man, Cap survived, though he blacked out, allowing HYDRA to capture him and the rest of the Howling Commandos, as well as obtain medical attention for Stucker. Iron Cross held Rogers still as he was escorted alongside Madame Hydra and Zola through the dungeon complex, before he left the Captain in Madame Hydra's care, being needed elsewhere.

Captain America and Iron Cross would cross paths once again when he attacked the Captain in defense of the Red Skull, who was trying to use the Cosmic Cube to awaken the Sleeper. Prepared for the battle this time, Rogers was able to redirect the blasts of Iron Cross' cannon back at him, stunning the suit long enough to make it vulnerable. While Captain America was no where near as strong as the mechanical suited warrior, who could do a massive amounts of damage with each strike, Cap was able to use his superior mobility to keep out of Iron Cross' attack radius and keep needling him. Eventually, the Red Skull himself intervened, firing his grenade launcher into the battlefield, but these grenades could do as much damage to Cross as they could to the Captain, and eventually Iron Cross' suit completely shut down. As Red Skull retreated, the cosmic cube in-hand and the Sleeper apparently awakening, Rogers threw himself at the Skull by using Iron Cross as a ramp, though the effort was in vain, and the Sleeper's attack knocked Cap away, allowing the Red Skull time to escape.

It is unknown what happened to Iron Cross after the Battle of Castle Zemo; whether he was able to survive when the Sleeper appeared to cause massive damage to the platforms he and Captain America were fighting on, and whether or not he ever saw the end of the World War II.