The long-tailed duck or oldsquaw (Clangula hyemalis) is a medium-sized sea duck. It is the only living member of its genus, Clangula; this was formerly used for the goldeneyes, with the long-tailed duck being placed in Harelda. An undescribed congener is known from the Middle Miocene Sajóvölgyi Formation (Late Badenian, 13–12 Mya) of Mátraszõlõs, Hungary.