Ace Attorney is a visual novel franchise developed by Capcom. With storytelling fashioned after legal dramas, the first entry in the series, Phoenix Wright: Ace Attorney, was released in 2001; since then five further main series games, as well as various spin-offs, prequels, and high-definition remasters for newer game consoles have been released. Additionally, the series has been adapted in the form of a live-action film and an anime; it is the base for manga series, drama CDs, musicals and stage plays. The player takes the roles of various defense attorneys, including Phoenix Wright, his mentor Mia Fey, as well as his understudies Apollo Justice and Athena Cykes who investigate cases and defend their clients in court. They find the truth by cross-examining witnesses and finding inconsistencies between the testimonies and the evidence they have collected. The cases last a maximum of three days; the judge determines the outcome based on evidence presented by the defense attorney and the prosecutor.

While the original Japanese versions of the games are set in Japan, the series' localizations are set in the United States (primarily Los Angeles) though retaining Japanese cultural elements. In the spin-off series Ace Attorney Investigations, the player takes the role of prosecutor Miles Edgeworth and in the prequel series, The Great Ace Attorney Chronicles, they play Phoenix's ancestor Ryunosuke Naruhodo.

The series was created by the writer and director Shu Takumi. He wanted the series to end after the third game, but it continued with Takeshi Yamazaki taking over as writer and director starting with Ace Attorney Investigations: Miles Edgeworth (2009). Takumi has since returned to write and direct some spin-off titles. The series has been well received, with reviewers liking the characters, story, and the finding of contradictions; it has also performed well commercially, with Capcom regarding it as one of their strongest intellectual properties. The series has been credited with helping to popularize visual novels in the Western world. As of December 31, 2024, the game series has sold 13 million copies worldwide.

The Ace Attorney series launched in Japan with the Game Boy Advance game Phoenix Wright: Ace Attorney in 2001, and has been published in the West since the release of a Nintendo DS port in 2005. The series currently consists of six main series games and five spin-offs.

The Ace Attorney games are visual novel adventure games in which the player controls defense attorneys and defends their clients in several different episodes. The gameplay is split into two types of sections, investigations and courtroom trials. During the investigations, the player searches the environments, gathers information and evidence, and talks to characters such as their client, witnesses, and the police. After enough evidence has been collected, the game moves on to a courtroom trial.

In the courtroom trials, the player aims to have their client declared "not guilty". They cross-examine witnesses, aiming to find lies and inconsistencies in the testimonies. They are able to go back and forth between the different statements in the testimony, and can press the witness for more details on a statement. When the player finds an inconsistency, they can present a piece of evidence that contradicts the statement. If the player is correct, the game presents a sequence that often starts with the protagonist shouting "Objection!" and pointing at the witness along with a shift in music before they begin to grill the witness with the inconsistency, which has become an iconic aspect of the series. Once enough evidence has been presented that conflicts the witnesses testimony, the witness will suffer a breakdown and reveal a major truth in the case. The player is penalized if they present incorrect evidence: in the first game, a number of exclamation marks are shown, with one disappearing after each mistake the player makes; in later games, a health bar that represents the judge's patience is used instead; and in 3DS games, the character's lawyer badge is used. If all exclamation marks or lawyer badges are lost, or the health bar reaches zero, the player loses the game and their client is found guilty.

Several Ace Attorney games introduce new gameplay mechanics to the series. Justice for All introduces "psyche-locks", which are shown over a witness when the player asks them about a topic they do not want to discuss; using a magatama, the player can start breaking the psyche-locks by showing the witness evidence or character profiles that proves they are hiding something. The number of psyche-locks depends on how deep the secret is; when all locks are broken, the topic becomes available, giving the player access to new information. Apollo Justice introduces the "perceive" system, where the player looks for motions or actions made by witnesses that show nervousness, similar to a tell in poker. Dual Destinies introduces the "mood matrix", through which the player can gauge the emotions of a witness, such as tones of anger when mentioning certain topics; if the player notices a contradictory emotional response during testimony, they can point out the discrepancy and press the witness for more information. Dual Destinies also introduces "revisualization", where the player reviews vital facts and forms links between evidence to reach new conclusions. Spirit of Justice introduces "divination séances", in which the player is shown the memories of victims moments before their deaths, and must find contradictions in the victim's five senses to determine what has happened. Professor Layton vs. Phoenix Wright: Ace Attorney introduces simultaneous cross-examinations of multiple witnesses, with the player being able to see and hear reactions from the different witnesses to the testimony and using this to find contradictions. The Great Ace Attorney introduces "joint reasoning", where the player finds out the truth by pointing out when their investigative partner Herlock Sholmes takes his reasoning "further than the truth".

The Ace Attorney Investigations spin-off series splits the gameplay into investigation phases and rebuttal phases, the latter of which is similar to the courtroom trials of the main series. During the investigation phases, the player searches for evidence and talks to witnesses and suspects. Things which the player character notice in the environment are saved as thoughts; the player can use the "logic" system to connect two such thoughts to gain access to new information. At some points, the player can create hologram reproductions of the crime scene, through which they can discover new information that would otherwise be hidden. Prosecutor's Gambit introduces "Mind Chess", where the player interrogates witnesses in a timed sequence that is visualized as a game of chess, with the player aiming to destroy the other character's chess pieces. To do this, they need to build up their advantage in the discussion by alternating between speaking and listening, and then choose to go on the offensive.