The Holarctic realm is the name for the biogeographic realm that encompasses the majority of habitats found throughout the northern continents of the world, combining Alfred Wallace's Palearctic zoogeographical region, consisting of North Africa and all of Eurasia (with the exception of the southern Arabian Peninsula, Southeast Asia, and the Indian subcontinent), and the Nearctic zoogeographical region, consisting of most of North America.
These regions are further subdivided into a variety of ecoregions. Many ecosystems, and the animal and plant communities that depend on them, are found across multiple continents in large portions of this realm. The continuity of these ecosystems results from the shared glacial history of the realm. The floristic Boreal Kingdom corresponds to the Holarctic realm.