The knob-billed fruit dove (Ptilinopus insolitus) is a species of bird in the family Columbidae. It is endemic to the Bismarck Archipelago.
The knob-billed fruit dove was originally described as Ptilopus insolitus by Hermann Schlegel in 1863 on the basis of specimens from New Ireland. The name of the genus was later emended to Ptilinopus. The generic name Ptilinopus is derived from the Ancient Greek words πτιλον (ptilon), meaning feather, and πους (pous), meaning foot. The specific name insolitus is from the Latin word insolitus, meaning strange. Knob-billed fruit dove is the official common name designated by the International Ornithologists' Union. Other common names for the species include knob billed fruit dove, knob-billed fruit-dove, red-knobbed fruit dove, red-knobbed fruit-dove, and Schlegel's fruit-dove.