Chondrosteus ("cartilage bone" in Greek) is a genus of extinct marine actinopterygian (ray-finned fish) belonging to the family Chondrosteidae.

[1] Chondrosteus is related to sturgeons and paddlefishes as part of the clade Acipenseriformes, and is one of the earliest known definitive members of the group.

[3] It is represented by a single species, C. acipenseroides, from the Blue Lias of Lyme Regis.

[2] The species Chondrosteus hindenburgi from the Toarcian (late Early Jurassic) of Germany was reallocated to the genus Strongylosteus.

Although some authors have suggested that the latter might be a junior synonym of Chondrosteus, there are no recent comparative studies on these two genera.