The Cuvier's beaked whale, goose-beaked whale, or ziphius (Ziphius cavirostris) is the most widely distributed of all beaked whales in the family Ziphiidae. It is smaller than most baleen whales yet large among beaked whales. Cuvier's beaked whale is pelagic, inhabiting waters deeper than 300 m (1,000 ft). It has the deepest and longest recorded dives among whales at 2,992 m (9,816 ft) and 222 minutes, though the frequency and reasons for these extraordinary dives are unclear. Despite its deep-water habitat, it is one of the most frequently spotted beached whales.

The species was named Ziphius cavirostris by Georges Cuvier, based on a skull fragment which he believed to be a fossil from an extinct species. He reused the genus name Ziphius from an undetermined species mentioned by historical sources. The species name cavirostris, from Latin cavus "hollow" and rostrum "beak", refers to a bony structure (cavity) anterior of the nares (the bones of the nose), now known as the prenarial basin. It is now known to be unique to males of this species.