Break Man

Break Man is an alias of Proto Man used in the first part of Mega Man 3. In this form, Proto Man's helmet covers all his head, taking a form near the same of the Sniper Joe's helmets (even the single eye). It is unknown what this "transformation" would change in Proto Man, but it is probably just a disguise. The key difference is that, in this form, Proto Man does not take damage from any special weapons. Only the Mega Buster can scratch him.

Proto Man will only appear as Break Man when all four Doc Robot stages are finished. After his defeat, Mega Man will return to Dr. Light's Lab, where Dr. Light says that Dr. Wily stole Gamma.

In the ending, Dr. Light, recognizing his characteristic whistle, reveals that Break Man is in fact Proto Man.

It seems that initially Proto Man was prepared to have an animation, which he transformed into Break Man, that was removed before the game release; he instead appears without making the transformation.