The Mountain Hare (Lepus timidus) is a hare, which is largely adapted to polar and mountainous habitats. It is distributed from Scandinavia to eastern Siberia; in addition there are isolated populations in the Alps, Ireland, Scotland, Wales and Hokkaido.

Whilst the fur is brown in summer, in preparation for winter this species moults into a white (or largely white) pelage. The Irish race (Lepus timidus hibernicus) in particular does not become completely white in winter.

Alternative common names include Blue Hare, Tundra Hare, Variable Hare, White Hare, Alpine Hare and Irish Hare.

The Alpine Hare is the provincial animal of Medelpadia in Sweden.

The Arctic Hare (Lepus timidus arcticus) is widely considered as a subspecies of the Mountain Hare. It is distributed over the tundra regions of Greenland and the northernmost parts of Canada. Some authorities regard the Arctic Hare as a separate species, L. arcticus. In the far north, it is white year-round; in other parts, it is a frosty blue grey colour in summer but the tail remains white.