Protosphyraena is an extinct genus of prehistoric marine pachycormiform that lived during the Upper Cretaceous (Coniacian-Maastrichtian). Although fossil remains have been found in both Europe and Asia, it is probably best known from the Smoky Hill Chalk of the Niobrara Formation of Kansas. It was built for speed, either steady cruising or sudden bursts after prey.
Protosphyraena shared the Cretaceous oceans with aquatic reptiles, such as mosasaurs and plesiosaurs, as well as with other prehistoric predatory fish. The name Protosphyraena is a combination of the Greek word protos ("early") plus Sphyraena, as paleontologists thought it was an ancient barracuda. Protosphyraena is not related to the swordfish, but belongs to the extinct family Pachycormidae.