The greylag goose (Anser anser) is a bird in the waterfowl family Anatidae. It has mottled and barred grey and white plumage and an orange beak and legs. A large bird, it measures between in length, with an average weight of . Its distribution is widespread, with birds from the north of its range in Europe and Asia migrating southwards to spend the winter in warmer places. It is the type species of the genus Anser and is the ancestor of one type of domestic goose, having been domesticated at least as early as 1360 BC.