The Arctic fox (Vulpes lagopus), also known as the white fox, polar fox, or snow fox, is a small fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome.

It is well adapted to living in cold environments. It has a deep thick fur which is brown in summer and white in winter.

Arctic foxes do not hibernate and are active all year round. They build up their fat reserves in the autumn, sometimes increasing their body weight by more than 50%. This provides greater insulation during the winter and a source of energy when food is scarce. They live in large dens in frost-free, slightly raised ground.

Arctic foxes tend to form monogamous pairs in the breeding season and maintain a territory around the den. Breeding usually takes place in April and May, and the gestation period is about 52 days. Litters tend to average five to eight kits, but exceptionally contain as many as 25 (the largest litter size in the order Carnivora). Both the mother and father help to raise the young which emerge from the den when 3 to 4 weeks old and are weaned by 9 weeks of age.