(species Gulo gulo, or sometimes G. luscus in North America), member of the weasel family (Mustelidae) that lives in cold northern latitudes, especially in timbered areas, around the world. It resembles a small, squat, broad bear 65–90 cm (26–36 inches) long, excluding the bushy, 13–26-centimetre tail; shoulder height is 36–45 cm, and weight is 9–30 kg (20–66 pounds). The legs are short, somewhat bowed; the soles, hairy; the semiretractile claws, long and sharp; the ears, short; and the teeth, strong. The coarse, long-haired coat is blackish brown with a light brown stripe extending from each side of the neck along the body to the base of the tail. The animal has anal glands that secrete an unpleasant-smelling fluid.

The wolverine is noted for its strength, cunning, fearlessness, and voracity. It may follow traplines to cabins and devour food stocks or carry off portable items; its offensive odour permeates the invaded cabin. The wolverine is a solitary, nocturnal hunter, preying on all manner of game and not hesitating to attack sheep, deer, or small bears. No animal except humans hunts the wolverine. Its fur is valued as trimming for parkas because frost and frozen breath can easily be brushed off the smooth hairs. Solitary during most of the year, the wolverine has a short courtship in February or March. A litter contains one to five young; the female's gestation period is about nine months.