Colonel

Colonel is the main attack leader of Repliforce, and brother of Iris. You will face him at least once. If you play X, you face him twice--once after you've beaten four Mavericks, and once in the Space Port, before entering the Final Weapon. In Zero's case, the first battle is merely a cinema scene, where Zero spares him for the sake of Iris, but in Space Port, Zero is forced to destroy him.