Quake is a 1996 first-person shooter game developed by id Software and published by GT Interactive. The first game in the Quake series, it was originally released for MS-DOS and Microsoft Windows, followed by Mac OS, Linux and Sega Saturn in 1997 and Nintendo 64 in 1998.

The game's plot is centered around teleportation experiments, dubbed slipgates, which have resulted in an unforeseen invasion of Earth by a hostile force codenamed Quake, which commands a vast army of monsters. The player takes the role of a soldier (later dubbed Ranger), whose mission is to travel through the slipgates in order to find and destroy the source of the invasion. The game is split between futuristic military bases and medieval, gothic environments, featuring both science fiction and fantasy weaponry and enemies as the player battles possessed soldiers and demonic beasts such as ogres or armor-clad knights. Quake heavily takes inspiration from gothic fiction and in particular the works of H. P. Lovecraft. The game went through many revisions during development, and had originally been inspired by a Dungeons & Dragons campaign held among id Software staff.

The successor to id Software's Doom series, Quake built upon the technology and gameplay of its predecessor. Unlike the Doom engine before it, the Quake engine offered full real-time 3D rendering and had early support for 3D acceleration through OpenGL. After Doom helped popularize multiplayer deathmatches, Quake added various multiplayer options. Online multiplayer became increasingly common, with the QuakeWorld update and software such as QuakeSpy making the process of finding and playing against others on the Internet easier and more reliable. Quake featured music composed by Trent Reznor and his band Nine Inch Nails.

Quake is often cited as one of the best video games ever made. Despite its critical acclaim, Quake's development was controversial in the history of id Software. Due to creative differences and a lack of leadership, the majority of the team left the company after the game's release, including co-founder John Romero. An "enhanced" version of Quake was developed by Nightdive Studios and published by Bethesda Softworks and was released for Nintendo Switch, PlayStation 4, Windows, and Xbox One consoles in August 2021, including the original game's first two expansions and two episodes developed by MachineGames. The PlayStation 5 and Xbox Series X/S versions were released in October 2021.

In Quake's single-player mode, players explore levels, facing monsters and finding secret areas before reaching an exit. Switches or keys open doors, and reaching the exit takes the player to the next level. Before accessing an episode, there is a set of three pathways with easy, medium, and hard skill levels. The fourth skill level, "Nightmare", was described by the game manual to be "so bad that the entry is hidden, so people won't wander in by accident".

Quake's single-player campaign is organized into four individual episodes with seven to eight levels in each (including one secret level per episode, one of which is a "low gravity" level that challenges the player's abilities in a different way). If the player's character dies, they must restart at the beginning of that level. The game may be saved at any time in the PC versions and between levels in the console versions. Upon completing an episode, the player is returned to the hub "START" level, where another episode can be chosen. Each episode starts the player from scratch, without any previously collected items. Episode one (which formed the shareware or downloadable demo version of Quake) has the most traditional layout with a boss in the last level. The ultimate objective at the end of each episode is to recover a magic rune. After all of the runes are collected, the floor of the hub level opens up to reveal an entrance to the "END" level which contains a final puzzle.

In multiplayer mode, players on several computers connect to a server (which may be a dedicated machine or on one of the player's computers), where they can either play the single-player campaign together in co-op (cooperative) mode, or play against each other in multiplayer (see LAN party). When players die in multiplayer mode, they can immediately respawn, but will lose any items that were collected. Similarly, items that have been picked up previously respawn after some time, and may be picked up again. The most popular multiplayer modes are all forms of deathmatch. Deathmatch modes typically consist of either free-for-all (no organization or teams involved), one-on-one duels, or organized teamplay with two or more players per team (or clan). Players frequently implement mods during teamplay. Monsters are not normally present in teamplay, as they get in the way and reveal the positions of the players.

The gameplay in Quake was considered unique for its time because of the different ways the player can manoeuvre through the game. Bunnyhopping or strafe-jumping allow faster movement, while rocket jumping enables the player to reach otherwise-inaccessible areas at the cost of some health. The player can start and stop moving suddenly, jump unnaturally high, and change direction while moving through the air. Many of these non-realistic behaviors contribute to Quake's appeal. Multiplayer Quake was one of the first games singled out as a form of electronic sport. A notable participant was Dennis Fong, who won John Carmack's Ferrari 328 at the Microsoft-sponsored Red Annihilation tournament in 1997.