The New Caledonian Giant Gecko, Leach's Giant Gecko or Leochianus gecko (Rhacodactylus leachianus), is a large species of gecko first described by Georges Cuvier in 1829. It is often commonly referred to as a Leachie gecko (plural Leachies). It is the largest of the Rhacodactylus geckos. At 14 inches (360 mm) total length, it is one of the largest geckos in the world, if not the largest, and is considered an example of island gigantism. R. leachianus is currently being evaluated for protected status by CITES. There are three recognized subspecies of R. leachianus: R. l. aubrianus, R. l. henkeli (first described by Seipp and Obst in 1994), and R. l. leachianus.
The leochianus gecko is a nocturnal arboreal gecko. It makes its home in the highest treetops on the island of New Caledonia. Its range includes all of the southern and eastern portions of the main island as well as several of the smaller islands in the group.
Many of the locals in New Caledonia call this gecko "the devil in the trees" because of the growling noises it makes.