Xiphiorhynchus is an extinct genus of prehistoric swordfish that lived from the Eocene until the Miocene. Unlike the modern swordfish, both the upper and lower jaws of Xiphiorhynchus were extended into blade-like points. The largest member of this genus, Xiphiorhynchus rotundus, was at least 5.1 meters in length and had an estimate weight of 708 kilograms, making it larger than any record extant billfish, and largest billfish ever known.

Fossils of Xiphiorhynchus have been found in: