Thief: Deadly Shadows is a stealth video game developed by Ion Storm for Microsoft Windows and Xbox. It is the third video game in the Thief series.

In Thief: Deadly Shadows the player takes the role of Garrett, a master thief. It is set in a fantasy world resembling a cross between the Late Middle Ages and the Victorian era, with more advanced technologies interspersed. One of the game's major new features was the ability to explore the City. While previous games sent Garrett straight from mission to mission, Thief: Deadly Shadows allows him to walk the City streets between missions where he can steal from passersby, spy on the townspeople's daily lives, and search for sidequests in addition to major story missions. The game also introduced an ability to switch between first and third person views, and to flatten against walls.

Development for both platforms started simultaneously. Like its predecessors, Thief: Deadly Shadows has received almost globally positive reviews. The level "Robbing the Cradle" received particular praise for its horror design. A follow-up to this game, Thief (formerly: Thief 4),[1][2] was released by Eidos Montreal in 2014.