一角鲸科，又称独角鲸科，在鲸目中种类较少，现存两属两种。两种都是中号鲸鱼，3-5米长，分布于北冰洋以及大西洋和太平洋北部。

The cetacean family Monodontidae comprises two unusual whale species, the narwhal, in which the male has a long tusk, and the dorsal fin-lacking, pure white beluga whale. They are native to coastal regions and pack ice around the Arctic Sea. Belugas can be found in the far north of the Atlantic and Pacific Oceans; the distribution of narwhals is restricted to the Arctic and Atlantic Oceans.