The Nicobar pigeon or Nicobar dove (Caloenas nicobarica, Car: ma-kūö-kö) is a bird found on small islands and in coastal regions from the Andaman and Nicobar Islands, India, east through the Indonesian Archipelago, to the Solomons and Palau. It is the only living member of the genus Caloenas alongside the extinct spotted green pigeon and Kanaka pigeon, and is the closest living relative of the extinct dodo and Rodrigues solitaire.

In 1738, the English naturalist Eleazar Albin included a description and two illustrations of the Nicobar pigeon in his A Natural History of Birds. When in 1758 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the tenth edition, he placed the Nicobar pigeon with all the other pigeons in the genus Columba. Linnaeus included a brief description, coined the binomial name Columba nicobarica and cited Albin's work. The species is now placed in the genus Caloenas erected by English zoologist George Robert Gray in 1840 with the Nicobar pigeon as the type species.

Two subspecies are recognised:

The two subspecies are very similar, with C. n. pelewensis being marginally smaller and with the elongated neck feathers being slightly shorter.

Based on cladistic analysis of mtDNA cytochrome b and 12S rRNA sequences, the Nicobar pigeon is sometimes called the closest living relative of the extinct didines (Raphinae), which include the famous dodo (Raphus cucullatus). However, the study's results showed this as one weak possibility from a limited sample of taxa. In any case, nDNA β-fibrinogen intron 7 sequence data agrees with the idea of the Raphinae as a subfamily of pigeons (and not an independent family, as was previously believed due to their bizarre apomorphies) that was part of a diverse Indopacific radiation, to which the Nicobar pigeon also belongs.

The following cladogram, from Shapiro and colleagues (2002), shows the Nicobar pigeon's closest relationships within Columbidae, a clade consisting of generally ground-dwelling island endemics.

A similar cladogram was published in 2007, differing only in the inverted placement of Goura and Didunculus, as well as in the inclusion of the pheasant pigeon and the thick-billed ground pigeon at the base of the clade.

C. nicobarica is a quite singular columbiform (though less autapomorphic than the flightless Raphinae), as are for example the tooth-billed pigeon (Didunculus strigirostris) and the crowned pigeons (Goura), which are typically considered distinct subfamilies. Hence, the Nicobar pigeon may well constitute another now-monotypic subfamily. And while any of the semi-terrestrial pigeons of Southeast Asia and the Wallacea cannot be excluded as possible closest living relative of the Raphinae, the Nicobar pigeon makes a more plausible candidate than for example the group of imperial-pigeons and fruit-doves, which seems to be part of the same radiation.