Quake II is a first-person shooter video game released in December 1997. It was developed by id Software and published by Activision. It is not a direct sequel to Quake; id decided to revert to an existing trademark when the game's fast-paced, tactile feel felt closer to a Quake game than a new franchise. The game's storyline is continued in its expansions and Quake 4.

Quake II takes place in a science fiction environment. In the single-player game, the player assumes the role of a Marine named Bitterman taking part in "Operation Alien Overlord", a desperate attempt to prevent an alien invasion of Earth by launching a counterattack against the home planet of the hostile Strogg civilization. Most of the other soldiers are captured or killed as soon as they approach the planned landing zone. Bitterman survives only because another Marine's personal capsule collided with his upon launch, causing him to crash far short of the landing zone. It falls upon Bitterman to penetrate the Strogg capital city alone and assassinate the Strogg leader, the Makron.