Tony Hawk's Underground is a skateboarding video game published by Activision in 2003, the fifth entry in the Tony Hawk's series. Neversoft developed the GameCube, PlayStation 2, Xbox versions, Beenox developed the Microsoft Windows version, which was released in Australia and New Zealand as a budget release in 2005, while the Game Boy Advance adaptation was developed by Vicarious Visions and Mobile version by Jamdat.
Underground is built upon the skateboarding formula of previous Tony Hawk's games: the player explores levels and completes goals while performing tricks. The game features a new focus on customization; the player, instead of selecting a professional skater, creates a custom character. Underground adds the ability for players to dismount their boards and explore on foot. The plot follows the player character and his or her friend Eric Sparrow as the two become well-known professionals and grow apart.
The game was developed with a theme of individuality, which was manifested in the extensive customization options, the presence of a narrative, and the product's characterization as an adventure game. Real-world professional skateboarders contributed their experiences to the plot. Upon release, the game was a major critical and commercial success, with reviewers praising its wide appeal, soundtrack, customization, multiplayer, and plot. The graphics and the controls for driving vehicles and walking were less well received. Underground's PlayStation 2 version had sold 2.11 million copies in the United States by December 2007. A sequel, Underground 2, was released in 2004.