Iron Monger Armor

The Iron Monger is the most common name used to refer to the armor developed and used by Obadiah Stane to fight the Iron Man armor. Its design is based on Tony Stark's Mark I design.

Iron Man
Pepper Potts, Phil Coulson, and several other agents of S.H.I.E.L.D. arrive at Obadiah's research facility after discover his secret plans. They spot the Mark I Armor and a storage location where something else was kept. Just then, a gigantic robotic suit comes to life and attacks them - it's Obadiah's counterpart suit, code-named the Iron Monger.

After he is about to kill Pepper, Tony discovers that Pepper is being attacked and has come to save her. The two ironclad warriors have a huge battle. Iron Man and the Iron Monger's battle soon transfers from Stark Tower to the streets. Iron Monger picks up a car and tries to throw it at Tony, but Tony is able to catch it and safely put it back down, and accidentally get run over as well. Iron Monger then uses a motorcycle instead and sucessfully makes Iron Man crash into a bus. He then sets the evacuated bus alight with one of his shoulder missiles. Tony is sent flying, but activates his updated rocket boosters just before he hits the wreckage. Tony is then chased hundreds of feet into the air by Stane, who also upgraded his own boosters. Stane manages to grab Tony, but is frozen as they go higher into the atmosphere. Tony uses this to scramble out of Stane's grasp and send him hundreds of feet down to the surface. However, by this point Tony has lost most of his power, and he tumbles back to earth as well.

Tony lands back at Stark Tower, right next to the skylight of the Arc Reactor. Stane soon follows, and they continue battling. Tony is caught in Stane's grasp once again, but is once again able to escape and rips out Stane's optical circuits. Stane removes his helmet and gloats that he has done what Stark could not: create the ultimate weapon, also known as his own suit, according to him. Tony keeps confronting Stane while telling Pepper to charge up the reactor. When Iron Monger has the upper hand and gets close to killing Tony, Pepper finally fires the Arc Reactor, sending a huge blast of energy so high it reaches the clouds, damaging the Iron Monger armor in the process. Stane is knocked unconscious by the blast, and he with his suit tumble into the generator, causing an explosion that kills him and destroys the armor.

Trivia

 * The character was called Iron Monger in the comics when he used his armor, but the codename is only referenced in the film when Stane describes himself and Stark as "iron mongers".
 * Iron Monger's suit in the film is actually based on Tony's first suit. In the comics he built the armor based around some design notes that Tony accidentally left behind.
 * In the armor, Obidiah's voice is enhanced to have a deep, intimidating tone in order to protect his identity.