Mega Man Battle Network[a] is a tactical role-playing video game series created by Masahiro Yasuma and developed and published by Capcom as a spin-off of the Mega Man series; it premiered in 2001 on the Game Boy Advance and takes place in an alternate continuity where computers and networking technology was the main focus on scientific advancement, rather than robotics.

Created amidst the success of Nintendo's and Game Freak's Pokémon series, alongside the rise of collectable card games, Mega Man Battle Network has players control MegaMan.EXE, a NetNavi operated by Lan Hikari as they attempt to stop the schemes of a net-crime organization called WWW (called "World Three"), headed by the universe's interpretation of Dr. Wily.

A compilation of all six mainline entries, Mega Man Battle Network Legacy Collection, was released in April 2023 for PlayStation 4, Nintendo Switch and PC.

Users are able to "jack in" to the Net and other computerized devices, and explore their various aspects using Digital people called "NetNavis (Network Navigators)" as if they were physical locations.

To progress through the games, the player must alternately navigate the outside world as Lan Hikari and the Net as MegaMan.EXE, each containing certain tasks that must be completed to allow advancement in the other.

[8] Controlling Lan, the player may travel around the world map, interact with non-player characters, check email, purchase items, initiate Net missions, or speak with MegaMan.EXE through his PET.

This cyber world is represented by a series of branching pathways and nodes, where MegaMan.EXE can travel to both new and previously visited locations, find and purchase items, and fight viruses.

Writer Masakazu Eguchi wrote that for the last three mainline entries, the developers primarily focused on evolving the battle system from the third game.

[18] Starting with Battle Network 4, the series began including content from Hideo Kojima's series Boktai, which was developed and published by Konami; the crossover content mainly included battle chips, bosses, and entire areas themed around Boktai and vampires.

[19] The music of Mega Man Battle Network was primarily composed by Akari Kaida,[20] Yoshino Aoki, and Toshihiko Horiyama.

The soundtracks for 1 through 6, alongside Battle Chip Challenge and the Japanese-only 4.5: Real Operation was released in 2021 on Spotify to celebrate the series' 20th anniversary.

Despite interference by Lan and MegaMan, the members stole the four element programs they needed in order to make it and succeeded in its creation.

In an attempt to make copies of Bass to create an army, the leader of Gospel overloaded energy to the bug fragments; but something went wrong and the concoction transformed into a giant wolf-like multi-bug organism.

[30] Released in December 2003 in Japan, and June 2004 in North America, Mega Man Battle Network 4 involves a meteor on trajectory towards Earth, and a new crime syndicate "Nebula" corrupting Navis with Dark Chips.

[32] Reception to Battle Network 4 was mixed-to-positive, although it too received lower review scores than the first three, which much criticism going to the lack of any real story outside of tournament scenarios.

[19] Reviewers generally showed little enthusiasm for Battle Network 6, with it being near-universally highlighted for its lack of changes from previous installments in terms of graphics and gameplay, although some praised its story.

[43] Reception to Network Transmission was divisive; a major point of contempt was the game's high difficulty, while the overall presentation drew mixed reactions.

The story adapts aspects of both the first Mega Man Battle Network game as well as the anime series, MegaMan NT Warrior.

Unlike other games, contemporary reception to Battle Chip Challenge was mostly negative, with many critics disliking the lack of audience participation and aging presentation, although the audio was praised.

[50] The "Real Operation" part of the title refers to how the Game Boy Advance functions as its own PET; during battles, players don't control the Navi directly, instead giving it instructions to follow.

[53] A compilation, Mega Man Battle Network Legacy Collection, was released in April 2023,[57] bringing the series to Nintendo Switch, PlayStation 4, and Windows.

An alternate English dub by Voiceovers Unlimited would air in South-East Asian countries, which followed the Japanese script more closely, and lacked the censorship NT Warrior had.

[66] Two separate manga series were created by Shogakukan and published in their monthly magazine CoroCoro Comics; MegaMan NT Warrior by Ryo Takamisaki which lasted for 13 volumes, and Battle Story MegaMan NT Warrior by Keijima Jun and Miho Asada which consisted of 4 volumes.