Dark Man is a series of four robots created by Dr. Wily in Megaman 5.
Dr. Wily created the Dark Men intending on getting his revenge on Proto Man for spoiling his last plan. He gave each Dark Man a different ability, the last one being able to shape-shift. This Dark Man disguised himself as Proto Man to frame him for his crimes, attacking the city with his army of Robot Masters. He kidnaps Dr. Light, leaving his scarf behind, making Mega Man believe that Proto Man became evil. Mega Man defeats his Robot Masters and goes after him on his castle. There, he fights the other three Dark Men, and finally meets with the fake Proto Man. Mega Man refuses to fight, but the fake shots at him. It's then that the real Proto Man appears and unmasks the Dark Man, so Mega Man fights him and defeats him, discovering that it was all another plan of Dr. Wily.