The Inaccessible Island Rail, Atlantisia rogersi, is a small bird of the rail family, Rallidae. It is found only on Inaccessible Island in the Tristan Archipelago, and is notable for being the smallest extant flightless bird in the world. Unlike many other islands, Inaccessible Island has remained free from introduced predators, allowing this species to flourish while many other flightless birds, including the even smaller Stephens Island Wren, have perished.

This rail has an average weight of 30 grams and a length of 17 centimeters. It is dark rusty-brown above and dark grey below, with a short black bill and a red eye.

This rail is found throughout Inaccessible Island, but prefers grassland and open fern-bush. Its diet includes earthworms, moths, berries, and seeds.

A clutch of two eggs is laid between October and January; chicks are vulnerable to predation by the Tristan Thrush.

The Ascension Flightless Rail (Mundia elpenor) which disappeared some time before 1700 but was briefly mentioned and described by traveller and hobby naturalist Peter Mundy in 1656 and Aphanocrex podarces, the St Helena Swamphen which disappeared before 1600 and has never been encountered by scientists were once considered congeners of A. rogersi. As they are considered to have evolved independently (with A. podarces probably not even being closely related), they have each been moved to a separate genus . Both species became extinct due to predation by introduced species, mainly cats and rats.