Tomás Ó Criomhthain was a native of the Irish-speaking Great Blasket Island near the coast of the Dingle Peninsula in Ireland. He wrote two Irish-language books, Allagar na h‑Inise, written over the period 1918–23 and published in 1928, and An tOileánach, completed in 1923 and published in 1929. Both have been translated into English. He is known as the "godfather" of Blasket Island writers. The 2012 translation by Garry Bannister and David Sowby is to date the only unabridged version available in English. In addition to his writings, Ó Criomhthain also provided content for Father George Clune's lexicon of the Munster Irish dialect, Réilthíní Óir.

The Great Blasket is the principal island of the Blaskets, County Kerry, Ireland. It was home to a small fishing community of Irish speakers until the island was abandoned in 1954 when living there became unsustainable.