The Atlantic puffin (Fratercula arctica), also known as the common puffin, is a species of seabird in the auk family. It is the only puffin native to the Atlantic Ocean; two related species, the tufted puffin and the horned puffin are found in the northeastern Pacific. The Atlantic puffin breeds in Russia, Iceland, Ireland, Norway, Greenland, Newfoundland and Labrador, Nova Scotia, and the Faroe Islands, and as far south as Maine in the west and France in the east. It is most commonly found in the Westman Islands, Iceland. Although it has a large population and a wide range, the species has declined rapidly, at least in parts of its range, resulting in it being rated as vulnerable by the IUCN. On land, it has the typical upright stance of an auk. At sea, it swims on the surface and feeds on small fish and crabs, which it catches by diving underwater, using its wings for propulsion.

This puffin has a black crown and back, pale grey cheek patches, and a white body and underparts. Its broad, boldly marked red-and-black beak and orange legs contrast with its plumage. It moults while at sea in the winter, and some of the brightly coloured facial characteristics are lost, with colour returning during the spring. The external appearances of the adult male and female are identical, though the male is usually slightly larger. The juvenile has similar plumage, but its cheek patches are dark grey. The juvenile does not have brightly coloured head ornamentation, its bill is narrower and is dark grey with a yellowish-brown tip, and its legs and feet are also dark. Puffins from northern populations are typically larger than in the south and these populations are generally considered a different subspecies.