Created by former military contractor Dr. Thomas Light for his Robot Master series as part of a pair of childlike robots designed to assist with domestic tasks and labwork, Rock was not originally meant to be the super fighting robot that he would eventually become. Unlike the other Robot Masters, Rock and Roll (named for Dr. Light's love of music) had no potential combat applications for their abilities, and thus they did not fall into the evil designs of their co-creator. Dr. Light's partner, a fellow roboticist named Dr. Albert Wily, had grown insanely jealous of the praise Dr. Light was recieving for the Robot Masters, praise that was not passed onto him; during their time as military contractors Wily had been fond dabbling in "unethical robotics experiments" of some kind, and thus his part in the Robot Master project was hushed down. Driven to the edge and wishing to show Light just who the real genius was, Wily reprogrammed the other six Robot Masters and attempted to use them in an insane attempt to at world conquest.

Unable to stand seeing his brothers used for such an unjust purpose, Rock begged Dr. Light to upgrade him for combat in order to save them and thwart Wily's evil schemes, and after some heavy thought and with much hesitation the good doctor finally agreed. With the upgrades complete, Rock was reborn as Mega Man, and with his new powers he defeated the rogue Robot Masters one by one before finally apprehending Wily. However, Wily soon broke out of captivity, aided by two experimental Robot Masters, and it wasn't long before Rock and the reprogrammed original six Robot Masters were able to defeat him again... But this time, Wily escaped, and set about building eight more Robot Masters with which to attempt his mad schemes at world domination and (more importantly) showing up Dr. Light once and for all. And again, Mega Man defeated him, leading him to run off into hiding once more.

But Dr. Wily wasn't the only one who was gunning for the Blue Bomber. Not long after defeating the mad scientist and gaining more and more acclaim as a hero, Rock accompanied Dr. Light to the Advanced Robotics Trade Show (ARTS) Convention, where the doctor was scheduled to take part in a debate about the future of robotics and artificial intelligence. Unfortunately for all involved, the ARTS Convention was targeted by the anti-robotics terrorist group known as the Emerald Spears, whose leader Xander Payne bore an insane grudge against all robots due to injuries sustained from Elec Man, one of the original six Robot Masters, during Wily's first attempt at supervillainy. With the help of Pharoah Man and Quake Woman, Robot Masters built by Dr. Light's old colleagues Dr. Cossack and Dr. Lalinde, Rock was able to disarm the bombs set by the Emerald Spears and ensure that all but Xander and a handful of other members of the Spears were arrested.

Now, Rock continues to fight for everlasting peace, even as the reknown of the Blue Bomber grows more and more. And somewhere, Dr. Wily is plotting another scheme and building more Robot Masters, and the day they face each other once more draws ever closer...

As a robot, Rock is stronger than his appearance would suggest, possessing low levels of superhuman strength, and he does not tire out or get exhausted like humans do (he does, however, eventually run out of power and thus requires occassional E-Tanks to continue running). As he was created to assist Dr. Light in the lab, he is not only proficient in most household tasks but has at least a basic knowledge of science, especially robotics.

As Mega Man, his armour provides him with additional protection, as well as giving him access to his primary weapon, the Mega Buster. An energy cannon that can be formed from either of his hands, it fires bullets of highly compressed solar energy. By charging up the Mega Buster for a few seconds, Mega Man is able to fire out a larger, more powerful shot than normal. Despite technically being able to form it from both hands simultaneously, his body is not able to handle the strain of two Mega Busters at once, and thus in the event of him ever doing this it will lead to him being critically damage after the shot is fired. The Mega Buster has practically infinite charge, and will continue functioning as long as Rock has at least some battery life left.

His most notable ability, however, is the Variable Weapon System. Using this, he is able to "download" additional weapons from other robots. Usually this is limited to just the Robot Masters, although other sufficiently advanced robots (for example, the Vision or Red Tornado) could possibly work with it. The weapon varies depending on the traits of the robot he downloaded it from, but is always at least somewhat linked to their abilities. For example, copying the super strong construction robot Guts Man gives him the Super Arm, which vastly increases his strength, whilst copying the literally hotheaded waste management robot Fire Man gives him the burning Fire Storm weapon. Unlike the Mega Buster, each weapon he downloads has only a finite charge.

Dr. Thomas Light: A world authority on robotics and artificial intelligence, and the genius scientist who built Rock and redesigned him into Mega Man. Rock and Dr. Light treat each other like father and son.

DLN-002 Roll Light: Rock's twin sister, like him she is a Robot Master designed for domestic tasks and labwork.

Dr. Light's Robot Masters: Cut Man, Guts Man, Bomb Man, Ice Man, Fire Man and Elec Man are all Robot Masters who were designed to perform various industrial or scientific purposes. Time Man and Oil Man were originally two experimental models. Despite all of them initially being reprogrammed by Dr. Wily to serve his evil purposes, once Mega Man defeated them they were restored to their original programming and functions, and occassionaly offer assistance to their brother when necessary.

Rush: Rock's robot dog, who sometimes assists him in the fight for everlasting peace.

Dr. Albert Wily: A former partner of Dr. Light, driven into supervillainy by an obsession to prove he possesses the superior intellect of the two. He serves as Mega Man's archnemesis, building his own evil Robot Masters to fight the Blue Bomber. Despite his rivalry with Dr. Light, he still respects his own partner; notably, he does not wish to see him dead, with the excuse that if he's dead he can't exactly gloat once he inevitably gets the better of him.

Wily's Robot Masters: Unlike the original set of Robot Masters, Metal Man, Air Man, Bubble Man, Quick Man, Crash Man, Flash Man, Heat Man and Wood Man were all designed primarily for combat; specifically, in an attempt to take down Mega Man, who Wily saw as the only obstacle between his plans to conquer the world and then rub it in Dr. Light's face.

DLN-000 Blues: Rock's older brother of sorts, the first Robot Master, created whilst Dr's Light and Wily were still military contractors. Rock has never met him, as Blues ran away from Light Labs for complicated reasons. He possesses an unstable power core, and Dr. Light sadly (yet incorrectly) believes that he has most likely ran out of power and deactivated by now.

Federal Agents Gilbert D. Stern and Roslyn Krantz: Two police officers who Rock first encountered shortly before Wily escaped from his first capture with the help of Time Man and Oil Man. Stern is your typical grizzled, cynical old cop, and possesses a distrust for modern technology, whilst Krantz is his younger, more idealistic and friendly partner.

LMN-001 Tempo ("Quake Woman"): The Robot Master creation of Dr. Lalinde, an old colleague of Dr. Light, and a good friend of Rock and Roll. Roll thinks that Tempo and Rock would make a cute couple, but the two would much rather prefer to just be friends.

Emerald Spears: An anti-robot terrorist group lead by Xander Payne, an ex-military recruit who lost an eye to Elec Man during Wily's initial attempt at world domination, leading him to develop an insane hatred of robots. They believe that technology (especially robotics and artificial intelligence) is advancing too quickly for humanity to keep up with it and, whilst they don't all share such extreme views as their leader, generally believe that anyone who is not with them is against them and thus feel little guilt for any civilian casualties that result from their activities.