Rhamphoichthys is an extinct genus of billfish-like plethodid ray-finned fish from Late Cretaceous (Cenomanian).

It contains one valid species, R. taxidiotis from the Hesseltal Formation of Germany and the Sannine Formation of Lebanon, in addition to two dubious species (R. minor from England and R. stebbingi from England & Italy) that are considered nomina nuda due to their fragmentary nature.

[1][2][3] Rhamphoichthys was a large, streamlined tselfatiiform fish with an elongated rostrum, akin to those of modern billfish and the co-occurring pachycormid fish Protosphyraena; the English and Italian species are only known from rostral fragments that were previously assigned to Protosphyraena.

However, unlike billfishes, it had a high pectoral fin and large scales on its body.

[1] Rhamphoichthys appears to have been a widespread and common apex predator in the Tethys and Boreal seas.