Stromerius is an extinct genus of basilosaurid early whale known from the Late Eocene (Priabonian, 37.2 to 33.9 million years ago) of Fayum, Egypt (29°36′N 30°36′E / 29.6°N 30.6°E / 29.6; 30.6, paleocoordinates 24°54′N 26°30′E / 24.9°N 26.5°E / 24.9; 26.5).

Stromerius is larger than the contemporary Saghacetus but smaller than the older Dorudon.

[3] Gingerich 2007 made S. nidensis the type species of the subfamily "Stromeriinae", but only mentioned this proposed subfamily briefly in his abstract.

[4] The genus is named for German palaeontologist Ernst Stromer von Reichenbach who made a ground-breaking work in the recovery of whale fossils in Egypt.

The species' name comes from Latin nidus, "nest", after the Arabic name of the type locality Garet el Esh, "hill of the nest".