A boss is an enemy-based challenge (and a computer-controlled opponent in such challenge) which is found in video games. A fight with a boss character is commonly referred to as a boss battle. Boss battles are generally seen at the climax of a particular section of the game, usually at the end of a stage or level, or guarding a specific objective, and the boss enemy is generally far stronger than the opponents the player has faced up to that point.
The first interactive game to feature a boss was dnd, a 1975 computer role-playing game for the PLATO system. One of the earliest dungeon crawls, dnd implemented many of the core concepts behind Dungeons & Dragons. The objective of the game is to retrieve an "Orb" from the bottommost dungeon. The orb is kept in a treasure room guarded by a high-level enemy named the Gold Dragon. Only by defeating the Dragon can the player claim the orb, complete the game, and be eligible to appear on the high score list.
The first arcade game to feature a boss was Phoenix, a fixed shooter developed by Taito in 1980. Phoenix includes five levels ("Rounds") which pit the player against swarms of alien birds. During the first two Rounds, the player is assaulted by the pigeon-like "Scouts", whereas the more formidable "Soldiers" are introduced in Rounds 3 and 4. On disposing these enemies, a giant mothership appears in the fifth and final Round.
Bosses are "super-powered" in comparison with regular enemies, and are usually found at the end of a level or area. Most games also include a "final" boss, which is usually the main antagonist in the story, at the very end of the game. Some well known final bosses are Bowser (Mario series), Doctor Robotnik (Sonic the Hedgehog), King DeDeDe (Kirby), Dr. Wily (Mega Man series), and Ganon (The Legend of Zelda). While most games include a mixture of boss opponents and regular opponents, some games have only regular opponents and some games have only bosses – for example, Shadow of the Colossus for the PlayStation 2 has no enemies other than bosses. In games such as Duke Nukem 3D, the first boss even reappears throughout the game as an uncommon enemy. However, they are weaker than the original.
Boss battles are typically seen as dramatic events. As such, they are usually characterized with unique music, and/or cutscenes before and after the boss battle. Recurring bosses and final bosses may have their own specific theme music, to distinguish them from other boss battles.
Some bosses require the player to defeat the bosses in a certain way that may be unusual to normal attacks, such as requiring the player to use a certain weapon (such as in Super Ghouls 'n Ghosts), or hit the boss on a certain part of the body (Metroid games are famous for these types of fights). Others of this type that are story-centered sometimes require certain prerequisites to be performed during the fight for the player to succeed, such as a requirement that a partner must stay alive during the battle or sequence to be counted as a victory. The most common games that have these requirements are the games in the Grand Theft Auto franchise, which players can usually have a partner during a mission that they must protect, and the final mission of Grand Theft Auto: San Andreas is an example of a boss battle that requires both a side character to remain alive and for additional actions to be taken in order to defeat him.
In some games, the final boss returns after being defeated, sometimes in a new form with alternate attacks, this can repeat a certain number of times before the player faces their final and most powerful form, after which they have beaten the game.
Some games also feature a sequence of consecutive boss battles as an extra challenge.
A miniboss, also known as a middle boss or midboss, is a boss smaller and usually weaker than the main boss in the area or level. Some well known video game characters who usually take the role of a miniboss are Dark Link ([The Legend of Zelda series), Vile (Mega Man X series), Allen O'Neil (Metal Slug) and Bowser Jr. (Mario). Minibosses are sometimes encountered later in the game as normal enemies.
A superboss is a type of boss most commonly found in RPG games. They are considered optional enemies (i.e. the boss plays a very small, if any, role in the game's main plot and the player is not required to fight the boss to complete the main game), although not all optional bosses are superbosses. They are generally much more powerful than the bosses encountered as part of the main game's plot or quest (typically having significantly more health and higher stats than the game's final boss), and often the player is required to complete a sidequest to gain access to the superboss battle. Superbosses are intended to give the player a challenge, to demonstrate mastery of the game. The most well-known examples appear in the Final Fantasy series of games, and include the Ruby and Emerald Weapons in Final Fantasy VII, Ultimate Weapon and Omega Weapon in Final Fantasy VIII, Ozma in Final Fantasy IX, Penance in Final Fantasy X, Yiazmat in Final Fantasy XII and Vercingetorix in Final Fantasy XIII. Sephiroth, Final Fantasy VII's main villain, appears as an optional boss in Kingdom Hearts and Kingdom Hearts II. Other examples of superbosses include Crawmerax the Invincible in the third Borderlands DLC, the King Statue in Mother 3 and Deadbeard in Golden Sun.
Some superbosses can also yield special items or skills that cannot be found any other way that can give a player a significant advantage during playthrough of the rest of the game, such as added experience or a superpowered weapon. Final Fantasy VIII's Ultima Weapon is an example of this. Players can draw the Eden summon monster from Ultima Weapon, which is the game's most powerful summon. Neither this summon nor the fight itself is required to complete the game, but getting them makes the game significantly easier than if the player goes without it.