Fossils of a spectacularly large (ca. 500 mm SVL) iguanid lizard were found in late Quaternary sediments on Fiji's main island Viti Levu. The lizard is distinct from the living Fiji iguanas, Brachylophus, by the presence of a parietal foramen located in the frontal bone, an anterior inferior alveolar foramen in the splenial, the possession of autotomic fracture planes in the caudal vertebrae, and much larger size. Like Brachylophus, this lizard appears to be basal among Iguanidae, but its relationship is unresolvable with the evidence available. This giant iguana probably became extinct in Fiji soon after the first human colonization about 3000 yr ago.