Army ant (or legionary ant or "Marabunta") means over 200 ant species. They are called army ants due to their aggressive predatory groups looking for food, known as "raids", in which many ants look for food at the same time in one place, attacking other animals collectively.

Army ants do not build a nest like most other ants. Instead, they build a living, temporary nest with their bodies. All army ant species are part of the ant family, Formicidae. There are several kinds that have evolved on their own the same behavior. This is called "legionary behavior", and is convergent evolution.