Mandroid

The Guardsmen are the armored guards of the Vault, a maximum security prison for superpowered humans.

Biography
The history of the Guardsmen is unknown.

When Iron Man targeted all armored warriors during the Armor Wars, this included the Guardsmen. There, he went into conflict with Hawkeye who tried to stop him.

Background
The first version of the Guardsmen outside the comics.

In the Comics
At first, the only Guardsman was Kevin O'Brien, whose armor was created by Stark to help Iron Man in case of emergency, but the untested brain interface drove Kevin mad, so he betrayed Iron Man and accidentally died in a fight.

Kevin's brother Michael tried to avenge him wearing the Guardsman armor, until he found the truth. He would later become security head of the Vault and all guards got Guardsman armor provided by Obadiah Stane.

It was Captain America, then using the name Captain, who fought Iron Man in the Vault.