Boreosomus (meaning: "boreal body") is an extinct genus of Triassic marine ray-finned fish.

It was first described from the Arctic island of Spitsbergen (Svalbard, Norway), hence its genus name, but was later also discovered in other parts of the world.

The type species is Boreosomus arcticus (= Acrolepis arctica Woodward, 1912).

Also typical for ptycholepids are the somewhat rectangular, horizontally arranged suborbital bones.

Fossils of Boreosomus were found, apart from Spitsbergen (Svalbard), in Greenland, Madagascar, China (Shaanxi), Spain (Catalonia), United States (Arizona), and Canada (British Columbia).