The Polynesian Rat or Pacific Rat (Rattus exulans), known to the Maori as Kiore, is the third most widespread species of rat in the world behind the Brown Rat and Black Rat.

The Polynesian Rat is similar in appearance to the Black Rat, but smaller, averaging around 12cm in body-length with a 13cm tail. Where it exists on smaller islands it tends to be smaller still. It is dark brown coloured, with a grey underside. It is nocturnal and omnivorous, eating seeds, fruit, leaves, bark, insects, lizards, and the eggs of birds. An adept climber, the Polynesian Rat has been known to nest in trees.

The Polynesian Rat is widespread throughout the Pacific and South-east Asia. They cannot swim over long distances and are therefore considered to be a significant marker of the human migrations across the Pacific, as the Polynesians accidentally or deliberately introduced them to the islands they settled.