Chelmon is a genus of marine ray-finned fish in the family Chaetodontidae, the butterflyfishes. They are tropical species native to the western Pacific Ocean.
There are currently three recognized species in this genus:
The only known potential fossil of this genus is Chelmon fossilis <small>de Beaufort, 1926</small> from the Miocene of Sulawesi, Indonesia. However, its placement within this genus is in doubt, although it is most likely a chaetodontid.