Salmo is a genus of ray-finned fish from the subfamily Salmoninae of family Salmonidae, and is part of the tribe Salmonini along with the sister genera Salvelinus and Salvethymus. Almost all Salmo species are native only in the Old World, the only exception being the Atlantic salmon, which is also naturally found across the North Atlantic in eastern North America.

Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon, trout, char, graylings, freshwater whitefishes, taimens and lenoks, all coldwater mid-level predatory fish that inhabit the subarctic and cool temperate waters of the Northern Hemisphere. The Atlantic salmon, whose Latin name became that of its genus Salmo, is also the eponym of the family and order names.