The Palearctic or Palaearctic is the largest of the eight ecozones constituting the Earth's surface. It consists of Europe, Asia north of the Himalaya foothills, northern Africa, and the northern and central parts of the Arabian Peninsula.

The Palearctic ecozone comprises the smaller terrestrial ecoregions of the European Siberian; the Mediterranean Basin; the Sahara and Arabian Deserts; Western and Central Asian; and East Asia. The Palaearctic ecozone also has numerous rivers and lakes, forming several freshwater ecoregions. Some of the rivers were the source of water for the earliest recorded civilizations that used irrigation methods.