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 zooplankton, 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.

Spending the autumn and winter in the open ocean of the cold northern seas, the Atlantic puffin returns to coastal areas at the start of the breeding season in late spring. It nests in clifftop colonies, digging a burrow in which a single white egg is laid. Chicks mostly feed on whole fish and grow rapidly. After about 6 weeks, they are fully fledged and make their way at night to the sea. They swim away from the shore and do not return to land for several years.

Colonies are mostly on islands with no terrestrial predators, but adult birds and newly fledged chicks are at risk of attacks from the air by gulls and skuas. Sometimes, a bird such as an Arctic skua or blackback gull can cause a puffin arriving with a beak full of fish to drop all the fish the puffin was holding in its mouth. The puffin’s striking appearance, large, colourful bill, waddling gait, and behaviour have given rise to nicknames such as “clown of the sea” or “sea parrot”. It is the official bird of the Canadian province of Newfoundland and Labrador.

The Atlantic puffin is a species of seabird in the order Charadriiformes. It is in the auk family, Alcidae, which includes the guillemots, typical auks, murrelets, auklets, puffins, and the razorbill. The rhinoceros auklet (Cerorhinca monocerata) and the puffins are closely related, together composing the tribe Fraterculini. The Atlantic puffin is the only species in the genus Fratercula to occur in the Atlantic Ocean. Two other species are known from the northeast Pacific, the tufted puffin (Fratercula cirrhata) and the horned puffin (Fratercula corniculata), the latter being the closest relative of the Atlantic puffin.

The generic name Fratercula comes from the Medieval Latin fratercula, friar, a reference to their black and white plumage, which resembles monastic robes. The specific name arctica refers to the northerly distribution of the bird, being derived from the Greek ἄρκτος (arktos), the bear, referring to the northerly constellation, the Ursa Major (Great Bear). The vernacular name “puffin” – puffed in the sense of swollen – was originally applied to the fatty, salted meat of young birds of the unrelated species Manx shearwater (Puffinus puffinus), which in 1652 was known as the “Manks puffin”. It is an Anglo-Norman word (Middle English pophyn or poffin) used for the cured carcasses. The Atlantic puffin acquired the name at a much later stage, possibly because of its similar nesting habits, and it was formally applied to Fratercula arctica by Pennant in 1768. While the species is also known as the common puffin, “Atlantic puffin” is the English name recommended by the International Ornithological Congress.