Duke Nukem Forever is a 2011 first-person shooter video game for Microsoft Windows, OS X, PlayStation 3 and Xbox 360 developed by 3D Realms and Triptych Games and finished by Gearbox Software and Piranha Games. It is a sequel to the 1996 game Duke Nukem 3D, as part of the long-running Duke Nukem video game series.

Intended to be groundbreaking, Duke Nukem Forever became a notable example of vaporware due to its severely protracted development schedule; the game was released in 2011 after fifteen years of development.