Asterosteus is a genus of rhenanid placoderm from the Eifelian. The type species, A. stenocephalus, is known from an incomplete skull from Middle Devonian strata in Ohio. What may be a second species ("Asterosteus sp <small>Schmidtt 1963</small>") is described from fragments decorated with star-shaped tubercules from the Eifelian-aged Gebze beds of Turkey.