We describe a new species of crocodile (Reptilia: Crocodyloidea: Mekosuchinae) from a maxilla recovered at the Arapus archaeological site, on the island of Efate, Vanuatu, South Pacific. As with mekosuchine species in New Caledonia and Fiji, Mekosuchus kalpokasi sp. nov. was a small, possibly terrestrial carnivore that is now extinct. The differences between the Efate specimen and previously described species of Mekosuchus warrant recognition of a new species. Based on its association with Efate's earliest known human inhabitants, dating approximately 3000 cal yr B.P., the extinction of M. kalpokasi and other insular mekosuchines may have been anthropogenic. The lack of adequately dated pre-Quaternary and Quaternary vertebrate fossil records from Vanuatu, New Caledonia, and Fiji (as well as other smaller islands) precludes determining the timing and route of dispersal of mekosuchine crocodyloids.