In the fictional universe of Mega Man, the classic Mega Man series consists of 10 main titles including the original game, as well as all Game Boy and PC titles featuring the original design of Mega Man/Rockman. The classic series is considered to be the origin of the story, with Mega Man being the first installment, and continuing with the direct sequels Mega Man 2-9 games. Chronologically after 8 comes Mega Man and Bass, and then comes Mega Man 9. There are also spinoff titles that do not relate to the series' storyline. The continuity of the Game Boy games' plots, as they relate to the main storyline, has never been confirmed officially. Although the classic series has yet to reach an ending, the storyline shifts to the Mega Man X series, followed by Mega Man Zero and finally Mega Man ZX. Although it is said that the Mega Man Legends series takes place sometime after the ZX series, there is an uncertain amount of time as to when it actually takes place. Mega Man Battle Network exists as an alternate universe or timeline. Another consisting event that occurs on the Mega Man Battle Network series which could probably confirm it's altern-universe plot is the coming of DUO, another fictional character that appears on Mega Man 8 and Battle network 4, with the difference of it not being intercepted by the evil-robotic form but for the humans. This could also mean that it is either the first or second time that Duo aims to the planet.[3] Mega Man Star Force follows the Battle Network series.

The character Mega Man was created in 1987 by Keiji Inafune at Capcom of Japan as the protagonist in a new style of platform game. In the story behind the original series, Rock is a robot created as a lab assistant by the scientist Dr. Thomas Light; following treachery by Dr. Wily, Rock was converted into a fighting robot to defend the world from Wily's violent robotic threats. Thus he becomes Mega Man (Rockman in the Japanese original). Though all Mega Man games feature unique stories, settings, and characters, they nevertheless share several common features that have made the series one of the most consistent in video game history. Until 1997, all Mega Man games were side scrolling, with 2D maze-like levels. The character controlled by the player was Mega Man himself, who had to fight through these levels using the "Mega Buster" (so named in Mega Man 4), a cannon attached to his arm, to shoot the robotic monsters that inhabited his environment. After defeating a Robot Master, the boss of a level, Mega Man would gain the ability to use that Robot Master's special weapon. Each robot master was themed after a specific element or object, for example "Fire Man," "Ice Man," "Stone Man," or "Napalm Man." The weapons Mega Man gained, in turn would share the theme of whomever it was he had just defeated. Levels can generally be completed in any order, and as a result determining the best strategic use of different weapons in different levels is one of the hallmarks of the series. Each new Mega Man game would contain new enemies, as well as familiar ones, new bosses (and thus weapons), and new gadgets. Enemies would have at least one weakness from certain weapons: for example, Ice Man's weapon is powerful against Fire Man. This creates a preferred order of stage completion. After all eight bosses are defeated, Mega Man travels to Wily's castle, and after fighting past clones of the eight bosses, confronts Wily, usually in his flying saucer. The classic series was the source material for two animated television series both apatly named "Mega Man" and featuring the heroes, villains, and themes of the games. The first show was a three- part OVA called "Mega Man: Upon a Star" developed in Japan, the other simply called "Mega Man", was developed specifically for North American audiences by animation studio Ruby-Spears.