Warhammer 40,000 is a miniature wargame produced by Games Workshop. It is the most popular miniature wargame in the world, and is particularly popular in the United Kingdom. The first edition of the rulebook was published in September 1987, and the 10th and current edition was released in June 2023.

As in other table top wargames, players wage battles using miniature models of warriors and fighting vehicles. The playing area is a tabletop model of a battlefield, comprising models of buildings, hills, trees, and other terrain features. Each player takes turns moving their model warriors around the battlefield and fighting their opponent's warriors. These fights are resolved using dice and simple arithmetic.

Warhammer 40,000 is set in the distant future, where a stagnant human civilisation is beset by hostile aliens and supernatural creatures. The models in the game are a mixture of humans, aliens, and supernatural monsters wielding futuristic weaponry and supernatural powers.