Mega Man 6, known in Japan as Rockman 6 Shijō Saidai no Tatakai!! (ロックマン6 史上最大の戦い!!, Rokkuman Shikkusu Shijō Saidai no Tatakai!!, lit. "Rockman 6: The Greatest Battle Ever!!"), is a video game developed by Capcom for the Nintendo Entertainment System (NES). It is the sixth installment in the original Mega Man series and was originally released in Japan on October 5, 1993 and in North America the following March. It was included in the Mega Man Anniversary Collection released in 2004. As of 2011, it has never been released in the PAL region.

The story of Mega Man 6 opens during a competitive robot fighting tournament with entrants from all around the globe. A villainous figure known as "Mr. X" announces he has reprogrammed the eight powerful contestants with intent to use them for taking over the world. The game's robotic protagonist Mega Man, who was sent to oversee the tournament, springs into action to foil X's plot. A standard action-platformer, Mega Man 6 plays nearly identically to its five predecessors with a few added features such as stages with alternate pathways and new Rush adaptors.

Mega Man 6 is the first game in the series to receive character design input from fans outside of Japan. This late-era game was also the last in the series released on Nintendo's 8-bit console. Due to the declining support of the NES and the growing presence of the newer and more powerful Super Nintendo Entertainment System (SNES), Capcom decided not to publish Mega Man 6 in North America. The North American version of Mega Man 6 was released by Nintendo of America instead. Critical reviews favored the game's comparable presentation and use of the established gameplay model from preceding chapters in the series, though nearly all judged it a redundant sequel.

While the first five Mega Man games are available on the Wii's Virtual Console, this game is absent from the Wii Shop Channel; however the game was released via the 3DS Virtual Console in Japan, with North America and Europe to follow soon in the near future.

The gameplay in Mega Man 6 is largely similar to its five NES counterparts. The player takes control of Mega Man to complete a series of side-scrolling platform stages littered with smaller robot enemies and occasional larger mini-bosses. The player's primary method of attack is the "Mega Buster" cannon, which can be charged for more powerful shots. At the end of each of the initial eight stages is a boss battle, where the player inherits that Robot Master's unique "Master Weapon" if successful. These eight levels can be completed in any order, although all Robot Masters are weak to a specific Master Weapon, adding an element of strategy to the order chosen by the player. The player's health is represented by a gauge that can be refilled by picking up energy pellets. Extra lives, reserve energy tanks, and pellets that refill Master Weapon power can also be found throughout each level. Mega Man 6 introduces the "Energy Balancer", which automatically refills the weapon with the lowest energy when picking up Master Weapon power.

Previous Mega Man games typically allowed the player to call on the transformable dog Rush or use other support items in order to traverse difficult or otherwise inaccessible parts of a stage. Mega Man 6 instead features a pair of "Rush Adaptors" that fuse Mega Man and Rush into special forms. The first, "Jet Mega Man", lets the player fly upward or hover for a brief period of time, but prevents the use of charge shots. The second, "Power Mega Man", utilizes a powerful, short-range punch attack for destroying large blocks. The player cannot slide when using either adapter. Mega Man 6 also presents less linear ways to complete the stages than in previous entries in the series. There are two pathways in many of the stages that lead to boss rooms, but the player is often required to use one of the Rush adaptors to begin an alternate route. Although either one will clear the stage, only one of them will give the player a letter circuit board for assembling the helper bird Beat. Collecting all four parts will allow the player to call on Beat to attack enemies.