The Iron is a customized version of the Iron Nokana created by Amadeus Syndicate. It is equipped with tank treads which allows the vehicle to move faster on any terrain, and has even more improved armor and firepower. Unlike the original Iron Nokana, the Iron lacks any hidden weapons underneath nor does it rise up.
There will be always a Masknell helping the Iron in battle. The fake Morden will constantly shoot rockets from his bazooka, and when he doesn't, he will enter the cockpit and fire a series of cannon rounds or homing missiles, open the front plate to use its spinning blade, or try to trample the player with the tank.
Players hit by the front plate when it is opening up will be knocked off to the ground. They won't lose a life, but their special weapons reverts to their pistol.
- Iron II - A purple version of the Iron that has had it's performance rapidly improved and its maneuvering technology made beyond comparison.
- Like all Metal Slug 4 bosses, it was made using old sprites from previous Metal Slug games.
- Though it is part of the "Iron Nokana" series, being a modified version, this vehicle's design greatly differs from that of its predecessors.