The black swallower, Chiasmodon niger, is a species of deep sea fish in the family Chiasmodontidae. It is known for its ability to swallow fish larger than itself.

It has a worldwide distribution in tropical and subtropical waters, in the mesopelagic and bathypelagic zones at a depth of 700–2,745 m (2,297–9,006 ft). It is a very common and widespread ocean fish; it is the most common fish species in the North Atlantic.