Dark Man

Darkman is actually a series of four robots created by Dr. Wily in Megaman 5.

Story
Dr. Wily created the Darkmans intending on getting his revenge on Protoman for spoiling his last plan. He gave each Darkman a different ability, the last one being able to shape-shift. This Darkman disguised himself as Protoman to frame him for his crimes, attacking the city with his army of Robot Masters. He kidnaps Dr. Light, leaving his scarf behind, making Megaman believe that Protoman became evil. Megaman defeats his Robot Masters and goes after him on his castle. There, he fights the other three Darkmans, and finally meets with the fake Protoman. Megaman refuses to fight, but the fake shots at him. It's then that the real Protoman appears and unmasks the Darkman, so Megaman fights him and defeats him, discovering that it was all another plan of Dr. Wily.