The Greylag Goose (also spelled Graylag in the United States), Anser anser, is a bird with a wide range in the Old World. It is the type species of thegenus Anser.
It was in pre-Linnean times known as the Wild Goose ("Anser ferus"). This species is the ancestor of domesticated geese in Europe and North America. Flocks of feral birds derived from domesticated birds are widespread.
The Greylag Goose is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.