The common goldeneye (Bucephala clangula) is a medium-sized sea duck of the genus Bucephala, the goldeneyes. Their closest relative is the similar Barrow's goldeneye.
Adult males ranges from 45–52 cm (18–20 in) and from 888 to 1,400 g (1.958 to 3.086 lb), while females range from 40–50 cm (16–20 in) and from 500 to 1,182 g (1.102 to 2.606 lb). The species is named for its golden-yellow eye. Adult males have a dark head with a greenish gloss and a circular white patch below the eye, a dark back and a white neck and belly. Adult females have a brown head and a mostly grey body. Their legs and feet are orange-yellow.