Tearaght Island or Inishtearaght (Irish: an Tiaracht) is an uninhabited steep rocky island west of the Dingle Peninsula. At longitude 10° 39.7' Tearaght is the westernmost of the Blasket Islands, and thus the westernmost island in both Ireland and the British Isles. However, there are some exposed rocks further west: Tearaght Rocks, Tearaght Rocks West (10° 41.0'), and Foze Rocks (10° 41.3').
An Tiaracht is about a kilometre from east to west, and 500 metres from north to south. The island is divided into two sections, a larger eastern part (200 metres high) and a western part that rises to 116 metres. A narrow neck of rock, with a natural tunnel through it, joins the two parts.
Like the other Blasket Islands, an Tiaracht holds large numbers of seabirds, with internationally important populations of Manx shearwater and European storm-petrel. Leach's storm-petrels have also been found there (but not proved to be breeding) in recent years. The number of auks, especially puffins, has apparently fluctuated greatly, though early records are not always reliable.