Oniichthys is an extinct genus of gar in the family Lepisosteidae.

It contains a single species, O. falipoui, known from the Late Cretaceous (Cenomanian) of Morocco.

[1] It is known from a few very well-preserved, near-complete specimens from the Kem Kem Formation, where it coexisted with the famous Spinosaurus.

[2] It closely resembles the modern genus Atractosteus, and is generally placed as its sister genus, a sister to Atractosteus and Lepisosteus, or even as a species within Atractosteus as per Grande (2010),[3] although this latter view has been disputed based on differences in skull morphology.

[4][5] The genus name references the Ooni, divine Yoruba kings, while the specific epithet honors Christian Falipou, who loaned one of the type specimens.