Grand Theft Auto: San Andreas is a 2004 action-adventure game developed by Rockstar North and published by Rockstar Games. It is the fifth main entry in the Grand Theft Auto series, following 2002's Grand Theft Auto: Vice City, and the seventh installment overall. It was released in October 2004 for the PlayStation 2, in June 2005 for Microsoft Windows and Xbox, and in November 2010 for Mac OS X. The game is set within an open world environment that players can explore and interact with at their leisure. The story follows former gangster Carl "CJ" Johnson, who returns home following his mother's murder and is drawn back into his former gang and a life of crime while clashing with corrupt authorities and powerful criminals. Carl's journey takes him across the fictional U.S. state of San Andreas, which is heavily based on California and Nevada and encompasses three major cities: Los Santos (inspired by Los Angeles), San Fierro (San Francisco) and Las Venturas (Las Vegas).

The game features references to many real-life elements of the world, such as its cities, regions, and landmarks, with its plot heavily based on several real-life events in Los Angeles in the early 1990s, including the rivalry between real-life street gangs, the crack epidemic of the 1980s and early 1990s, the LAPD Rampart scandal, and the 1992 Los Angeles riots. Unlike its predecessor, San Andreas introduced gameplay elements that were incorporated in later games, including RPG-style mechanics, customisation options with both clothing and vehicle appearances, a vast array of activities and mini-games, and the inclusion of gambling games.

Considered by many reviewers to be one of the greatest video games ever made, San Andreas received critical acclaim upon release, with praise directed at its music, story and gameplay, and criticism for its graphics and some aspects of its controls. It was the best-selling video game of 2004, and with over 27.5 million copies sold worldwide as of 2011, it is the best-selling PlayStation 2 game and one of the best-selling video games of all time. Like its predecessors, San Andreas is cited as a landmark in video games for its far-reaching influence within the industry. The game's violence and sexual content was the source of much public concern and controversy. In particular, a player-made software patch, dubbed the "Hot Coffee mod", unlocked a previously hidden sexual scene, resulting in the game being re-rated AO by the North American Entertainment Software Rating Board (although its previous M rating was reinstated after the game was edited to remove the content). A remastered version of the game was released for Android and iOS in 2013, for Windows Phone, Fire OS and Xbox 360 in 2014, and for PlayStation 3 in 2015. In June 2018, the game was made available for the Xbox One via backward compatibility. An enhanced version with the subtitle The Definitive Edition was released in 2021, and a virtual reality version for Oculus Quest 2 is in development. The next main entry in the series, Grand Theft Auto IV, was released in April 2008.