Yellow Devil

Yellow Devil (イエローデビル), also known as Rock Monster, is one of Dr. Wily's creations, originally a fortress boss in the first Mega Man game. Consisting of a large yellow blob, he can dismantle himself and cross the screen to attack his enemies. His weak point is his eye.

The Yellow Devil can be very difficult to defeat, with a complicated attack pattern.

In the remake Mega Man Powered Up, it is revealed that the Yellow Devil can talk, but the only thing he can say is "Bumo". His pattern is different from the original.

In the arcade games Mega Man: The Power Battle and Mega Man 2: The Power Fighters, he appears as the penultimate boss of the courses "Mega Man 1~2" and "Mega Man 3~6" from Power Battle and "Rescue Roll!" from Power Fighters. He has new attacks such as shooting beams from His eye, separating into smaller versions of himself, walking, jumping, throwing part of his body that bounce across the room, and absorbing players from his arm to launch them.

Yellow Devil is one of the three enemy racers (the others being a Roader and Sniper Joe) in Mega Man: Battle and Chase, and there is a secret boss recolor of him called Black Yellow Devil (ブラックイエローデビル), sometimes shortened to Black Devil.

He makes a cameo appearance in the opening scene of Mega Man 8.

Other media
Yellow Devil appeared in the manga Mega Man Megamix. After the defeat of Dr. Light's six Robot Masters, Yellow Devil holds Mega Man and he meets Dr. Wily. Wily tries to convince Mega Man join him, but as he refuses, he orders Yellow Devil to crush him. Mega Man manages to escape Yellow Devil's grip by using Guts Man's strength, breaking his arm, and than finishes him off with a Thunder Beam.

Trivia

 * The music that plays during the Yellow Devil battle in Mega Man: The Power Battle and Mega Man 2: The Power Fighters is a remix of the music from Dr. Wily first two stages in Mega Man.
 * In the U.S., Yellow Devil's name was changed to Rock Monster due to a policy Nintendo had against religious references in NES games at the time.