Clymenoptilon is an extinct genus of phaethontiform bird related to modern tropicbirds.

It contains a single species, C. novaezealandicum from the Paleocene-aged Waipara Greensand of New Zealand.

Its name references Clymene, the mother of Phaethon in Greek mythology.

It is the earliest known phaethontiform from the Southern Hemisphere (living only a few million years after the Cretaceous-Paleogene extinction event), suggesting that the group may have originated in Zealandia.

It lived alongside the early pseudotooth bird Protodontopteryx, also one of the oldest representatives of its order.