Contrary to its name, the little-known pygmy killer whale is actually a member of the dolphin family. Until 1952 the pygmy killer whale was only known from two skulls collected in the 19th century, and while more specimens have been collected since it remains one of the least known of the small cetaceans. It has a slender, cigar-shaped body that tapers to the tail fin, with a round, blunt head that lacks the beak of many dolphin species. The pygmy killer whale is dark grey to black, with lighter sides and a dark 'cape' that extends down the back. Its lips are edged with white and the moderately long flippers are rounded at the tips.