Timber or grey wolves are the largest wild members of the dog family. They generally have grizzled coats, with gray, black, and light brown fur covering their head and upper body, and yellowish white fur on the legs and belly. Thick winter undercoats give them the appearance of added bulk; when they shed in the spring, they look thin. They have bushy tails, legs longer than coyotes' and dogs' legs, and oversized paws.

Timber wolves' head and body length is 1 to 1.5 meters, plus a tail one-third to half a meter. Their weight varies greatly by subspecies, ranging from 18 to 79 kg, with an average between 27 to 45 kg.

Historically, wolves have the largest range of any land mammal, other than people. They have lived in all habitats in the Northern Hemisphere except for tropical forest. Wolves are carnivores, often preying on animals larger than they are, including elk, caribou, and deer, as well as beavers, hares, and other small animals.