Dragon Quest, previously published as Dragon Warrior in North America until 2005, is a series of role-playing video games created by Japanese game designer Yuji Horii (Armor Project), character designer Akira Toriyama (Bird Studio), and composer Koichi Sugiyama (Sugiyama Kobo) and published by Square Enix (formerly Enix). Since its inception, development of games in the series have been outsourced to a plethora of external companies until the tenth installment, with localized remakes and ports of later installments for the Nintendo DS, Nintendo 3DS, and Nintendo Switch being published by Nintendo outside of Japan. With its first game published in 1986, there are eleven main-series games, along with numerous spin-off games. In addition, there have been numerous manga, anime and novels published under the franchise, with nearly every game in the main series having a related adaptation.

The series introduced a number of features to the genre and has had a significant impact on the development of other role-playing games. Installments of the series have appeared on various computers, consoles, handheld devices, and mobile phones. Early in the series, the Dragon Quest games were released under the title Dragon Warrior in North America to avoid trademark conflict with the unrelated tabletop role-playing game DragonQuest. Square Enix did not register the Dragon Quest trademark for use in the United States until 2002.

The basic premise of most Dragon Quest games is to play a hero (actually named "Hero" in spinoff fiction, but in all games, the player is able to name their hero) who is out to save the land from peril at the hands of a powerful evil enemy, with the hero usually accompanied by a group of party members. Common elements persist throughout the series and its spinoff games: turn-based combat; recurring monsters, including the Slime, which became the series' mascot; a text-based menu system; and random encounters in most of the main series.

All games in the series as of 2024 involve scenario writer and game designer Yuji Horii, and prior to their deaths, character designer Akira Toriyama and music composer Koichi Sugiyama have handled their respective roles on most games in the series. The original concepts, used since the first game, took elements from the Western role-playing games Wizardry and Ultima. A core philosophy of the series is to make the gameplay intuitive so that players can easily start playing the games. The series features a number of religious overtones which were heavily censored in the NES versions outside of Japan.

The first installment of the franchise was released in Japan on May 27, 1986, titled with the name "Dragon Quest" followed by a Roman numeral. Since 1986, the franchise has featured eleven games within the main series, as well as several spin-off games, and also two animated productions.^{[citation needed]}

The first four Dragon Quest installments were released for the Famicom and Nintendo Entertainment System in Japan and North America, respectively. The first two installments were released in Japan on the Famicom and ported that same year to the MSX; all four games have been remade for newer systems. Dragon Quest was first released in Japan on May 27, 1986, and in North America as Dragon Warrior in August 1989. Dragon Quest II Akuryō no Kamigami was released in Japan in 1987 and in North America in 1990 as Dragon Warrior II. Dragon Quest III Soshite Densetsu e... was released in Japan in 1989 and North America as Dragon Warrior III in 1992. Dragon Quest IV was released in Japan in 1990 and in North America in 1992 as Dragon Warrior IV. A 2001 Japanese PlayStation remake of Dragon Warrior IV scheduled for the North American market was never released. The Nintendo DS remake of Dragon Quest IV was released in North America, Europe, and Australia under its original translated title; the European release removed the number from the title.

Two games were released for the Super Famicom: Dragon Quest V in 1992 and Dragon Quest VI in 1995; both have been re-released on newer systems. Dragon Quest V was originally scheduled for release in North America but was canceled amid rumors that Enix had given up on the American market. No official reason was ever given. The Nintendo DS remakes were released in North America with Dragon Quest V also being released in Europe and Australia, the latter without the numbering. One game was released for the PlayStation: Dragon Quest VII: Eden no Senshi-tachi in 2000 in Japan and 2001 in North America under the title Dragon Warrior VII. Dragon Quest VIII: Journey of the Cursed King was released for the PlayStation 2 in 2004 in Japan, 2005 in North America, and 2006 in Europe and Australia, again without the number in the title for Europe. Dragon Quest VIII was the first game in the series to be released in North America under the title of Dragon Quest, and the first European release of a main series game. Dragon Quest IX, the only game in the series initially released on the Nintendo DS, was originally released in 2009 in Japan, and in 2010 in North America, Europe, and Australia. Dragon Quest X was announced for the Wii in December 2008. In September 2011, Square Enix announced that Dragon Quest X would also be released on the Wii U, with Nintendo 3DS connectivity. It is the first MMORPG in the series, and the only numbered Dragon Quest game not released outside Japan. Dragon Quest XI was released in Japan on July 29, 2017, and worldwide on September 4, 2018.

Dragon Quest XII: The Flames of Fate was announced in 2021. According to Horii, the game will have a darker tone, feature more meaningful choices, and overhaul the traditional Dragon Quest turn-based combat. Dragon Quest XII will also be the first mainline title released after the deaths of series music composer Koichi Sugiyama and character designer Akira Toriyama who had been involved with the series since its inception.^{[citation needed]}