Tom Clancy's Splinter Cell: Chaos Theory is a stealth game, developed and published by Ubisoft. Chaos Theory is the third game in the Splinter Cell series endorsed by writer Tom Clancy.

The game follows the covert activities of Sam Fisher, an agent working for a covert-ops branch within the NSA called "Third Echelon". Though originally announced for release in Fall 2004, the actual release date was March 2005 for the Xbox, PlayStation 2, GameCube and Microsoft Windows. Handheld versions for the Nintendo DS and N-Gage have also been released. A version for the Game Boy Advance was planned, but later cancelled. Actor Michael Ironside reprised his role as Sam, while Don Jordan returned from the original game to voice Lambert, having been replaced by Dennis Haysbert in Tom Clancy's Splinter Cell: Pandora Tomorrow. The game went gold on March 22, 2005 for all platforms. Official Xbox Magazine considered Splinter Cell: Chaos Theory to be Xbox "Game of the Year" (2005) for its outstanding gameplay and lifelike graphics. A remake called Tom Clancy's Splinter Cell 3D was released for the Nintendo 3DS. A remastered, high-definition, version of Tom Clancy's Splinter Cell: Chaos Theory was released for the PlayStation Network for the PlayStation 3 on December 20, 2010 as part of the Splinter Cell Trilogy.