Mega Man

Mega Man is the titular protagonist of the Mega Man video game series. In his own series, Mega Man was originally created in the year 200X as a robot named Rock to be Dr. Light's lab assistant. However, when Light's jealous colleague Dr. Wily had taken Dr. Light's industrial robots and reprogrammed them for evil, Rock volunteered to be converted into a battle robot to combat them, being dubbed Mega Man.

In the Mario series, Mega Man has only made appearances in the Club Nintendo comics, and is set to be a playable character in Super Smash Bros. for Nintendo 3DS / Wii U as a third-party character.

Club Nintendo comics
Mega Man's first appearance in Mario-related media is in "Super Mario: Die Bescherung". The comic shows him with several other characters at Mario and Luigi's Christmas party.

His first and only major appearance was in the 1993 comic "Super Mario: Die Verwandlung", where he serves as Dr. Light's assistant. Besides taking care of the doctor and welcoming his visitors, Mega Man also drives the car they use for catching Wario.

Mega Man is also mentioned in the comic "Super Mario: Mario im Wunderland". When Mario and Toad meet Kirby, the latter explains that he wants to see the wizard so that he can wish to look like Mega Man.

Super Smash Bros. for Nintendo 3DS / Wii U
After twenty years of not appearing in any Mario-related media, Mega Man has been confirmed to be a playable guest character in the upcoming Super Smash Bros. for Nintendo 3DS / Wii U. Mega Man's appearance and aesthetics in this game are based on his appearance in the NES titles, possessing a moveset centered on shooting his opponents; he can use the Mega Buster to fire multiple single shots, or use the Charge Shot as a side smash attack. His only melee attacks are the slide move, making its debut in Mega Man 3, and the Mega Upper, a move introduced in Mega Man 2: The Power Fighters which later appeared in Marvel vs. Capcom. His recovery is the Rush Coil, a common ability in the Mega Man series that is introduced in Mega Man 3. Mega Man is the third third-party character to be playable in the Super Smash Bros. series. His Final Smash involves him summoning Mega Man X, MegaMan.exe, MegaMan Volnutt and Star Force Mega Man to shoot a merged energy beam.

He can also use various Robot Master abilities from his series. These include:
 * Super Arm, from the original Mega Man, as a throw.
 * Metal Blade, which operates similarly to its Mega Man 2 incarnation, though the projectiles can be picked up and thrown.
 * A tornado-based move (possibly Air Shooter from Mega Man 2) as an aerial up projectile.
 * Leaf Shield, also from Mega Man 2.
 * Crash Bomber, also from Mega Man 2, which operates identically to the Gooey Bomb from Super Smash Bros. Brawl.
 * Top Spin from Mega Man 3, which is a spinning attack, similar to Meta Knight's Mach Tornado from Super Smash Bros. Brawl.
 * Hard Knuckle as a Meteor Smash, which can be fired as a projectile just like in Mega Man 3.
 * Spark Shock and Flame Blast, from Mega Man 3 and Mega Man 6 respectively, uniquely utilize both Mega Busters in Mega Man's arms though using either one causes the Busters to open up and vent out excess heat; the venting of the Busters originates from Super Adventure Rockman.
 * Slash Claw from Mega Man 7 and Flame Sword from Mega Man 8 as aerial-based melee attacks.

Trivia

 * Mega Man series creator Keiji Inafune took some level of inspiration from Mario when designing his own series.