- "Bumo... Bumomomo! Bumomo Bumomomomo Bumo!"
- ―Yellow Devil, Mega Man Powered Up
Yellow Devil (イエローデビル Ierō Debiru?), also known as Rock Monster or Yellow Demon, is a gigantic robot, the first combat robot created by Doctor Albert W. Wily, originally appearing as a fortress boss in the first Mega Man game. Its body consists of yellow goo-like shape-memory parts that can dismantle and fly across the screen to attack his enemies. Its only weak point is its red eye.
Video game appearances
The Yellow Devil can be very difficult to defeat, due to its complicated attack pattern, and its tendency to change forms after getting hit once or twice. His weakness is the Thunder Beam.
In the remake of the original game, it is revealed that the Yellow Devil can talk, but the only thing it can say is "Bumo", which it says in various ways in order to form its own language. Cut Man attempts to speak to 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 though the Yellow Devil has a mission, he has his own mission, too. Oil Man just copies its "bumo"s. Bomb Man doesn't understand what he says and tells him to speak in a "language that can be understood".
Its attack pattern in New Style is different from the original. On Easy Mode, it will just stand in one place and reveal its eye to shoot energy spheres. On Normal, it splits into several parts like the original game. The same attack pattern is repeated on Hard, but it can also fire a laser beam at the player either from the ground or the wall. To avoid the ground laser, the player has to stand at the wall and jump at the correct time. To dodge the wall laser, the player just has to run near him. Sometimes it will try to crush the player with its hand. It is weak to the Fire Storm.
Yellow Devil appears as the penultimate boss of the "Mega Man 1~2" and "Mega Man 3~6" courses. In the "Mega Man 1~2" course, it jumps back and forth and sometimes takes on a round form and attack with a laser. It still splits into nine parts that fly across the room, throwing a cube-shaped part of its body that bounces across the room, slam enemies with its hand to pull the target into its body and launch them at high speed, and blasting its upper body into four fists diagonally to punch foes. Its weakness is the Super Arm.
In the "Mega Man 3~6" course, the Devil only jumps back and forth. After taking a small amount of damage, the Yellow Devil splits into three smaller versions of itself with horns. One of the miniatures will stay the ground, jumping around and firing three small projectiles or splitting in three parts. The other two miniatures will walk around the ceiling and attack by releasing three large energy spheres. After the small version in the ground takes some damage, it will jump to the ceiling and change places with the other miniatures. After all three receive enough damage, the Yellow Devil will reform and jump around the room. It is weak to Gyro Attack.
Yellow Devil is the penultimate boss of "Rescue Roll!" course. Its attack pattern is similar to the "Mega Man 1~2" course from The Power Battle, except that its splitting attack changed and the four-way fist blast was removed. It can walk and defend against attacks in this game. It is weak to Thunder Beam.
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 Burakku Ierō Debiru?), sometimes shortened to Black Devil.
The Yellow Devil appears in the fourth installment of the Super Smash Bros. franchise. He acts as the main stage hazard in Wily Castle, deployed from the castle itself in the background. It behaves and fights exactly like its 8-bit counterpart, firing blasts of energy from its single eye and splitting up into multiple projectiles to reform on the other side. Players can choose to fight it by attacking the exposed eye, its only weak spot. If defeated, the Yellow Devil will release a highly damaging explosion, which will count as an attack for the player who dealt the final blow.
- Yellow Devil has a cameo appearance in the opening cutscene of Mega Man 8.
- The Yellow Devil was shown in the first trailer of Rockman Online, but the game's cancellation as well as lack of footage featuring it makes it impossible to determine where it was intended to appear and what role he was supposed to play.
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 Buster||Rolling Cutter||Super Arm||Ice Slasher||Hyper Bomb||Fire Storm||Thunder Beam|
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) start of the story. The battle's conclusion is shown in the fourth issue. Mega Man destroys the Devil with the Mega Buster as he doesn't want to use the weapons copied from the Robot Masters. Despite its defeat, the concept of Yellow Devil would inspire further evil creations, including the Chaos Devil and the Ra Devil. The former was created by combining Yellow Devil technology with the creature Chaos in a cooperative effort between Wily and Dr. Eggman, Chaos being a native of Eggman's world. The Ra Devil was created as an improvement upon Wily's design by Ra Moon, who sought to turn Wily's own work against him as the doctor had attempted to do by creating Ra Thor. Mega Man later faced an improved version when attacking Dr. Wily's newest castle
Prior to the Worlds Collide crossover event, Yellow Devil did not make an appearance in the Short Circuits series. During the crossover, however, it did appear in one of the Off Panel strips of the Sonic the Hedgehog series, in which it is seen talking to Tikal the Echidna, who attempts to convince it that violence is not the answer to its problems. It later returned in Worlds Unite in Sonic Universe #77's Off Panel strip, crammed in with various characters from Sonic the Hedgehog/Sonic Universe, Sonic Boom, Mega Man, and Mega Man X.
Yellow Devil is the large robot who stands guard within the main control room of Wily's fortress. Its 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. All the Yellow Devil can say is the letter "W".
After the defeat of Doctor Thomas Light's six Robot Masters in the story "The Birth of Mega Man", Yellow Devil holds Mega Man hostage 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 its arm, and then finish it off with a Thunder Beam.
Yellow Devil appears in Wily's fortress. All it says is "Gururu".
- A glitch in the original release of the first game allows the player to quickly defeat Yellow Devil by shooting it with the Thunder Beam and repeatedly tapping the pause button when it makes contact. Every time pause is toggled it will register a hit.
- In the U.S., Yellow Devil's name was changed to "Rock Monster" in early sources due to a policy Nintendo had against religious references in NES games at the time.
- Artist Ryan Jampole of the Archie Comics featured a modified Yellow Devil in part of a series of Halloween costumes drawn for Roll, in which the Yellow Devil appeared as the Big Daddy to Roll's Little Sister from Bioshock. 
- The Yellow Devil appears with several other characters on the cover of Mega Man #50; it is unknown if it will be featured in Worlds Unite.
|The "Devil" series robots|
| Yellow Devil • Black Yellow Devil • Yellow Devil MK-II • New Yellow Devil • Green Devil • Grey Devil • Dark Moon |
Twin Devil • Petit Devils • Block Devil • Shadow Devil • Rainbow Devil • Lava Demon • Steel Devil • Chaos Devil
|List of Robot Masters|
|Cut Man • Guts Man • Ice Man • Bomb Man • Fire Man • Elec Man|
|Yellow Devil • Copy Robot • CWU-01P • Wily Machine 1|
|Mega Man's Special Weapons|
|Rolling Cutter • Super Arm • Ice Slasher • Hyper Bomb • Fire Storm • Thunder Beam|
|Mega Man's Support Items|
|List of Enemies|
|Adhering Suzy • Blaster • Big Eye • Bunby Heli • Bombombomb • Changkey • Crazy Razy • Foot Holder • Gabyoall • Kamadoma|
Killer Bomb • Flying Shell • Metall • Pepe • Pickelman • Screwdriver • Sniper Joe • Super Cutter • Watcher
|Game Script • List of Enemies • Damage Data Chart • Miscellaneous Data|
|Mega Man Powered Up|
|List of Playable Characters|
| Mega Man (Mega, S, C) • Roll • Proto Man |
Cut Man • Guts Man • Ice Man • Bomb Man • Fire Man • Elec Man • Time Man • Oil Man
|List of Robot Masters|
|Cut Man • Guts Man • Ice Man • Bomb Man • Fire Man • Elec Man • Time Man • Oil Man|
|Yellow Devil • CWU-01P • Copy Robot • Wily Machine|
|Mega Man's Special Weapons|
|Rolling Cutter • Super Arm • Ice Slasher • Hyper Bomb • Fire Storm • Thunder Beam • Time Slow • Oil Slider|
|Other Weapons and Support Items|
|Magnet Beam • Clock Hand • Mega Kick • Roll Swing • Proto Strike|
|Walkthrough • Damage Data Chart • Game Script • Enemies|
|Mega Man: The Power Battle|
|Mega Man • Proto Man • Bass|
| - Mega Man 1~2 -|
Cut Man • Guts Man • Ice Man • Crash Man • Heat Man • Wood Man
- Mega Man 3~6 -
Magnet Man • Gemini Man • Dust Man • Gyro Man • Napalm Man • Plant Man
- Mega Man 7 -
Freeze Man • Junk Man • Cloud Man • Slash Man • Shade Man • Turbo Man
- Dr. Wily -
| Rolling Cutter • Super Arm • Ice Slasher • Crash Bomber • Atomic Fire • Leaf Shield|
Magnet Missile • Gemini Laser • Dust Crusher • Gyro Attack • Napalm Bomb • Plant Barrier
Freeze Cracker • Junk Shield • Thunder Strike • Slash Claw • Noise Crush • Scorch Wheel
|Damage Data Chart • Script|
|Mega Man 2: The Power Fighters|
|List of Playable Characters|
|Mega Man • Proto Man • Bass • Duo|
|List of Bosses|
| - Search for Wily! -|
Shadow Man • Plant Man • Gyro Man • Centaur Man • Bubble Man • Heat Man
- Rescue Roll! -
Cut Man • Stone Man • Shade Man • Elec Man • Dive Man • Slash Man
- Recover the new parts! -
Guts Man • Pharaoh Man • Air Man • Quick Man • Gemini Man • Napalm Man
- Dr. Wily -
|List of Special Weapons|
| Shadow Blade • Plant Barrier • Gyro Attack • Centaur Arrow • Bubble Lead • Atomic Fire|
Rolling Cutter • Power Stone • Noise Crush • Thunder Beam • Dive Missile • Slash Claw
Super Arm • Pharaoh Wave • Air Shooter • Quick Boomerang • Gemini Laser • Napalm Bomb
|Rush • Beat • Treble|
|Super Smash Bros. for Nintendo 3DS / Wii U|
|Mega Man's Weapons and Moves|
|Mega Buster • Sliding • Mega Upper • Charge Shot • Super Arm • Metal Blade • Leaf Shield • Air Shooter • Crash Bomb|
Hard Knuckle • Top Spin • Spark Shot • Flame Blast • Slash Claw • Flame Sword
|Hyper Bomb • Ice Slasher • Shadow Blade • Skull Barrier • Plant Barrier • Danger Wrap • Tornado Hold|
|Other properties included in Super Smash Bros Nintendo 3DS / Wii U|
|- Sonic the Hedgehog -|
|Sonic the Hedgehog • Tails • Knuckles the Echidna • Shadow the Hedgehog • Green Hill Zone • Chaos Emeralds • Super transformation|
|- Street Fighter -|
|Ryu • Hadoken • Shoryuken|
|- Nintendo (Miscellaneous) -|