Yellow Devil

Yellow Devil (イエローデビル), also known as Rock Monster or Yellow Demon, 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 only weak point is his eye.

Mega Man
The Yellow Devil can be very difficult to defeat, due to his complicated attack pattern, and his tendency to change forms after getting hit once or twice. His weakness is the Thunder Beam.

Mega Man Powered Up
In the Mega Man remake, Mega Man Powered Up, it is revealed that the Yellow Devil can talk, but the only thing he can say is "Bumo", which he says in various ways in order to form his own language. Cut Man attempts to speak it, but without much success as it only seemed to insult the monster. Ice Man appears to understand what the Yellow Devil is saying, however, and says that even that the Yellow Devil has his mission, he has his own mission, too. Oil Man just copies his "bumo"s. Bomb Man doesn't understands what he says and tells him to speak in a "language that can be understood". His attack pattern is different from the original. On Hard Mode he fires a laser beam at the player either from the ground or the wall. To avoid the ground one, the player has to stand at the wall and jump at the correct time and to dodge the wall one the player just has to run under him.

The Power Battle & The Power Fighters
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 a part of his body that bounces across the room, and absorbing players with his arm to launch them.

Mega Man: Battle & Chase
Yellow Devil is one of three enemy racers (the others being a Roader and Sniper Joe). There is also 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.

Super Smash Bros 4
The Yellow Devil is set to appear in an unknown capacity. The only footage seen of him was at the end of the Mega Man trailer, which shows him forming and Mega Man trying to hit him in the eye. The blobs seem to come from the top of the screen as opposed to the sides of the screen though.

Other appearances
Yellow Devil has a cameo appearance in the opening cutscene of Mega Man 8.

Damage Data Chart
Displays the amount of damage in units that Yellow Devil will receive from each Special Weapon from the original Mega Man.

Mega Man Megamix
Yellow Devil is the large robot who stands guard within the main control room of Wily's fortress. His body parts are composed of an organic ferromagnetic polymer gel, and each part is controlled by a nucleus-like core. Changes in the magnetic field allow it to take on the distinctive Yellow Devil form. What appears to be its eye is the main core that controls its entire body. Wily believed Yellow Devil to be his greatest creation ever, but due to the fact that Yellow Devil's core could be disrupted by a strong electromagnetic pulse, the Thunder Beam proved to be his ultimate weakness.

After the defeat of Dr. Light's six Robot Masters in the story "The Birth of Mega Man", Yellow Devil holds Mega Man as he meets Dr. Wily. Wily tries to convince Mega Man to 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 then finishes him off with a Thunder Beam.

Mega Man (Archie Comics)
The Yellow Devil appears in the first issue when Mega Man is entering Wily's fortress, however during the fight, the scene cuts to the (chronological) beginning of the story.

The battles conclusion is shown in the fourth issue. Mega Man destroys him with the Mega Buster as he doesn't want to use the weapons copied from the Robot Masters.

Rockman Online
Although the Yellow Devil was shown in the first trailer, the game's cancellation as well as lack of footage make it impossible to determine where he appears and what role he plays.

Trivia

 * A glitch in the original release of the first Mega Man game allows the player to quickly defeat Yellow Devil by shooting him with the Thunder Beam and repeatedly tapping the pause button when it makes contact. Every time pause is toggled it will register a hit.


 * 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 the first two Wily stages in the original 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.


 * In most of his appearances in different Mega Man titles, Yellow Devil's primary weakness tends to be electricity-themed weapons. The Green Devil and Shadow Devil bosses from Mega Man 8 and Mega Man X5 also have an electric-based weakness; Thunder Claw and Tri-Thunder respectively, with Tri-Thunder acting almost identically to his weakness in the original Mega Man, the Thunder Beam.

Yellow Devil