Phoenix Wright: Ace Attorney is a visual novel adventure game developed and published by Capcom. It was released in 2001 for the Game Boy Advance in Japan and has been ported to multiple platforms. The 2005 Nintendo DS version, titled Gyakuten Saiban Yomigaeru Gyakuten in Japan, introduced an English language option, and was the first time the game was released in North America and Europe. It is the first entry in the Ace Attorney series; several sequels and spin-offs were produced, while this game has seen further ports and remasters for computers, game consoles, and mobile devices.

The story follows Phoenix Wright, a rookie defense attorney who attempts to have his clients declared "not guilty". Among other characters are Phoenix's boss, Mia Fey; his assistant and Mia's sister, Maya; and prosecutor Miles Edgeworth. The player controls Phoenix through two sets of sections: investigations and courtroom trials. During investigations they gather information and evidence. During trials they cross-examine witnesses, and answer questions from the judge, the prosecutor, and the witnesses. The story is split into five cases. The fifth was introduced in the Nintendo DS version to take advantage of gameplay elements using the handheld's touchscreen not available in the original Game Boy Advance version.

A team of seven developed the game over the course of ten months. Written and directed by Shu Takumi, it was originally planned as a Game Boy Color game about a private investigator. The game was designed to be simple; Takumi wanted it easy enough that even his mother could play. While the original version of the game takes place in Japan, the localization is set in the United States; this became an issue when localizing later games, where the Japanese setting was more obvious.

Generally, the game has been positively received by critics who praised its premise, writing, characters, and presentation. The game has been a commercial success both in Japan and internationally. The release sales in North America broke expectations, and as a result the software became difficult to find in stores shortly after its release. Other media based on the game have been produced. It has been credited with helping to popularize visual novels in the Western world, and has been cited as one of the greatest games ever made. A manga series premiered in 2006, a film adaptation of the game, titled Ace Attorney, premiered in 2012, and an anime series adaptation aired in 2016.

A high-definition version of the first three Ace Attorney games, Phoenix Wright: Ace Attorney Trilogy HD, was released for iOS and Android in Japan on February 7, 2012, and for iOS in the West on May 30, 2013. Another collection of the first three games, Phoenix Wright: Ace Attorney Trilogy, was released for the Nintendo 3DS in Japan on April 17, 2014, in North America on December 9, 2014, and in Europe on December 11, 2014. It was also released for Nintendo Switch, PlayStation 4, and Xbox One on February 21, 2019, in Japan, and on April 9, 2019, internationally; a Windows version was released internationally on the same date.

Phoenix Wright: Ace Attorney is a visual novel adventure game where the player takes the role of Phoenix Wright, a rookie defense attorney, and attempts to defend their clients in five cases. These cases are played in a specific order. After finishing them, the player can re-play them in any order. Each case begins with an opening cinematic cutscene often depicting a murder; shortly thereafter, the player is given the job of defending the prime suspect in the case. The gameplay is divided into two sections, investigations and courtroom trials.

During investigations, which usually take place before or between trial sessions, the player gathers information and evidence by talking to characters such as their client, witnesses, and the police. The player can move a cursor to examine various things in the environment. By using a menu the player can move to different locations, examine evidence, and present evidence to other characters. By showing certain pieces of evidence to some witnesses, the player can access new information.

A fifth case titled "Rise from the Ashes" was created for the Nintendo DS version (and included in all subsequent releases), which is a post-credits bonus episode that is unlocked when the main game is completed. In "Rise from the Ashes" the player is able to examine evidence more closely, rotating it to view it from all sides, and zooming in or out on it using touchscreen controls; they are also able to move a cursor to investigate specific parts of the evidence. The fifth case is significantly longer than the other episodes, and it also features forensics tests the player can use at crime scenes to find clues. The player can spray luminol by tapping areas they want to examine on the touch screen allowing them to see otherwise invisible blood stains. They can touch the touch screen to apply aluminum flake powder to search for finger prints. After applying it, they can blow into the microphone to reveal the prints. Once the player has gathered enough evidence, the investigation section ends.