The macaques (pronounced /məˈkæk/) constitute a genus (Macaca, /məˈkækə/) of Old World monkeys of the subfamily Cercopithecinae.

Aside from humans (genus Homo), the macaques are the most widespread primate genus, ranging from Japan to Afghanistan and, in the case of the Barbary Macaque, to North Africa. Twenty-two macaque species are currently recognised, and they include some of the monkeys best known to non-zoologists, such as the Rhesus Macaque (as the Rhesus Monkey), Macaca mulatta, and the Barbary Macaque (as the Barbary Ape), M. sylvanus, a colony of which lives on the Rock of Gibraltar. Although several species lack tails, and their common names therefore refer to them as apes, these are true monkeys, with no greater relationship to the true apes than any other Old World monkeys.

Several species of macaque are used extensively in animal testing

In the late 1990s it was discovered that nearly all (about 90%) pet and captive macaques are carriers of the herpes B virus. This virus is harmless to macaques, but infections of humans, while rare, are potentially fatal. A 2005 University of Toronto study showed that urban performing macaques also carried simian foamy virus, suggesting they could be involved in the species-to-species jump of similar retroviruses to humans.

Macaques also have a very intricate social structure and hierarchy. If a macaque who is lower level in the social chain has eaten berries and there is none left for the higher level macaque, then the one higher in status can, within this social organization, remove the berries from the other monkey's mouth