The wolf is the largest wild extant member of the family Canidae, and is further distinguished from other Canis species by its less pointed ears and muzzle, as well as a shorter torso and a longer tail.

Of all members of the genus Canis, the wolf is most specialized for cooperative game hunting as demonstrated by its physical adaptations to tackling large prey, its more social nature, and its highly advanced expressive behaviour, including individual or group howling.

Wolves have a long history of interactions with humans, having been despised and hunted in most pastoral communities because of their attacks on livestock, while conversely being respected in some agrarian and hunter-gatherer societies.

[12] In 2019, a workshop hosted by the IUCN/Species Survival Commission's Canid Specialist Group considered the New Guinea singing dog and the dingo to be feral Canis familiaris, and therefore should not be assessed for the IUCN Red List.

[30] In 2021, a genetic study found that the dog's similarity to the extant grey wolf was the result of substantial dog-into-wolf gene flow, with little evidence of the reverse.

Wolves in northern climates can rest comfortably in open areas at −40 °C (−40 °F) by placing their muzzles between the rear legs and covering their faces with their tail.

[52] Black-coloured wolves in North America acquired their colour from wolf-dog admixture after the first arrival of dogs across the Bering Strait 12,000 to 14,000 years ago.

Wolves live in forests, inland wetlands, shrublands, grasslands (including Arctic tundra), pastures, deserts, and rocky peaks on mountains.

[68] They are known to eat the berries of mountain-ash, lily of the valley, bilberries, cowberries, European black nightshade, grain crops, and the shoots of reeds.

[82] Wolves more broadly affect cougar population dynamics and distribution by dominating territory and prey opportunities and disrupting the feline's behaviour.

The canine parvovirus, which causes death by dehydration, electrolyte imbalance, and endotoxic shock or sepsis, is largely survivable in wolves, but can be lethal to pups.

Leptospirosis can be contracted through contact with infected prey or urine, and can cause fever, anorexia, vomiting, anemia, hematuria, icterus, and death.

In the rare cases where other wolves are adopted, the adoptee is almost invariably an immature animal of one to three years old, and unlikely to compete for breeding rights with the mated pair.

[105] Wolves howl to assemble the pack usually before and after hunts, to pass on an alarm particularly at a den site, to locate each other during a storm, while crossing unfamiliar territory, and to communicate across great distances.

When building dens, females make use of natural shelters like fissures in rocks, cliffs overhanging riverbanks and holes thickly covered by vegetation.

Wolves have been killed while attempting to bring down bison, elk, moose, muskoxen, and even by one of their smallest hoofed prey, the white-tailed deer.

[126] The wolf must give chase and gain on its fleeing prey, slow it down by biting through thick hair and hide, and then disable it enough to begin feeding.

[125] Wolves may wound large prey and then lie around resting for hours before killing it when it is weaker due to blood loss, thereby lessening the risk of injury to themselves.

[127] With medium-sized prey, such as roe deer or sheep, wolves kill by biting the throat, severing nerve tracks and the carotid artery, thus causing the animal to die within a few seconds to a minute.

This has fostered recolonization and reintroduction in parts of its former range as a result of legal protection, changes in land use, and rural human population shifts to cities.

[41] Wolves were given protection under the Endangered Species Act (ESA) of 1973, and have since returned to parts of their former range thanks to both natural recolonizations and reintroductions in Yellowstone and Idaho.

[161] The Ancient Romans connected the wolf with their god of war and agriculture Mars,[162] and believed their city's founders, Romulus and Remus, were suckled by a she-wolf.

Although Aesop used wolves to warn, criticize and moralize about human behaviour, his portrayals added to the wolf's image as a deceitful and dangerous animal.

[172] The tale of "Little Red Riding Hood", first written in 1697 by Charles Perrault, is considered to have further contributed to the wolf's negative reputation in the Western world.

[174] The hunting of wolves, and their attacks on humans and livestock, feature prominently in Russian literature, and are included in the works of Leo Tolstoy, Anton Chekhov, Nikolay Nekrasov, Ivan Bunin, Leonid Pavlovich Sabaneyev, and others.

[177] Farley Mowat's largely fictional 1963 memoir Never Cry Wolf is widely considered to be the most popular book on wolves, having been adapted into a Hollywood film and taught in several schools decades after its publication.

[186] The most frequently targeted livestock species are sheep (Europe), domestic reindeer (northern Scandinavia), goats (India), horses (Mongolia), cattle and turkeys (North America).

Predatory attacks can occur at any time of the year, with a peak in the June–August period, when the chances of people entering forested areas (for livestock grazing or berry and mushroom picking) increase.

[200] Historic methods included killing of spring-born litters in their dens, coursing with dogs (usually combinations of sighthounds, Bloodhounds and Fox Terriers), poisoning with strychnine, and trapping.

[201][202] A popular method of wolf hunting in Russia involves trapping a pack within a small area by encircling it with fladry poles carrying a human scent.