The Inaccessible Island rail is a small bird of the rail family, Rallidae. Endemic to Inaccessible Island in the Tristan Archipelago in the isolated south Atlantic, it is the smallest extant flightless bird in the world. The species was formally described by physician Percy Lowe in 1923 but had first come to the attention of scientists 50 years earlier. The Inaccessible Island rail's taxonomic affinities and origin were a long-standing mystery; in 2018 its closest relative was identified as the South American dot-winged crake, and it was decided that both species are best classified in the genus Laterallus.

Tristan da Cunha, colloquially Tristan, is a remote group of volcanic islands in the South Atlantic Ocean. It is the most remote inhabited archipelago in the world, lying approximately 2,787 kilometres (1,732 mi) from Cape Town in South Africa, 2,437 kilometres (1,514 mi) from Saint Helena, 3,949 kilometres (2,454 mi) from Mar del Plata in Argentina, and 4,002 kilometres (2,487 mi) from the Falkland Islands.