The Labrador duck (Camptorhynchus labradorius) is an extinct North American duck species. It has the distinction of being the first known endemic North American bird species to become extinct after the Columbian Exchange, with the last reported sighting occurring in 1878 in Elmira, New York, and the last preserved specimen was shot in the fall of 1875 in Long Island, New York, by J.G. Bell. It was already a rare duck before European settlers arrived, and as a result of its rarity, information on the Labrador duck is not abundant, although some, such as its habitat, characteristics, dietary habits and reasons behind its extinction, are known. There are 55 specimens of the Labrador duck preserved in museum collections around the globe.

The Labrador duck was also known as the pied duck and skunk duck, the former being a vernacular name that it shared with the surf scoter and the common goldeneye (and even the American oystercatcher), a fact that has led to difficulties in interpreting old records of these species. Both names refer to the male's striking white/black pied plumage. Yet another common name was sand shoal duck, referring to its habit of feeding in shallow water.

The Labrador duck is considered a sea duck. A basic difference in the shape of the process of metacarpal I divides the sea ducks into two groups:

The position of the nutrient foramen of the tarsometatarsus also separates the two groups of sea ducks. In the first group, the foramen is lateral to the long axis of the lateral groove of the hypotarsus; in the second, the foramen is on or medial to the axis of that groove.

The closest evolutionary relatives of the Labrador duck were thought to be the scoters (Melanitta), though its close ecological similarity to Steller's eider had already been noted earlier. A mitogenomic study of the placement of the Labrador duck confirmed the species to be closely related to Steller's eider, as shown below.

The female plumage was grey. Although weakly patterned, the pattern was scoter-like. The male's plumage was black and white in an eider-like pattern, but the wings were entirely white except for the primaries. The trachea of the male was scoter-like. An expansion of the tracheal tube occurred at the anterior end, and two enlargements (as opposed to one enlargement as seen in scoters) were near the middle of the tube. The bulla was bony and round, puffing out from the left side. This asymmetrical and osseus bulla was unlike that of scoters; this bulla was similar to eiders and harlequin duck's bullae. The Labrador duck has been considered the most enigmatic of all North American birds.

The Labrador duck had an oblong head with small, beady eyes. Its bill was almost as long as its head. The body was short and depressed with short, strong feet that were far behind the body. The feathers were small and the tail was short and rounded. The Labrador duck belongs to a monotypic genus.

The Labrador duck migrated annually, wintering off the coasts of New Jersey and New England in the eastern United States, where it favored southern sandy coasts, sheltered bays, harbors, and inlets, and breeding in Labrador and northern Quebec in the summer. John James Audubon's son reported seeing a nest belonging to the species in Labrador.^{[citation needed]} Some believe that it may have laid its eggs on the islands in the Gulf of Saint Lawrence. The breeding biology of the Labrador duck is largely unknown.