Liam Ó Rinn (20 November 1886 – 3 October 1943; born William J. Ring, also known by the pen name Coinneach) was a civil servant and Irish-language writer and translator, best known for "Amhrán na bhFiann", a translation of "The Soldier's Song", the Irish national anthem, which has almost eclipsed Peadar Kearney's English-language original.
Ó Rinn was born in Ballybough, Dublin, one of five sons and one daughter of Patrick Ring, a Dublin Metropolitan Police officer from Kilkenny, and his wife Elizabeth (née Griffith) from Laytown, County Meath. He attended St. Joseph's Christian Brothers School in Fairview, leaving aged 14 to work as a solicitor's clerk. He studied Irish with the Gaelic League, where he worked from c.1907 to 1920. He took part in the Easter Rising and was interned at Frongoch until December 1916. He was interned for a year in the Irish War of Independence. He wrote articles in Irish from 1914 and published books from 1920. He translated news stories in the Freeman's Journal in 1922–24, when he went to work in the Free State Oireachtas' translation department, producing Irish versions of official documents, including the 1922 constitution and the current 1937 constitution. He learned French, German, Spanish, Welsh, and Russian, and translated works from several Continental authors. He married Ellen Fennelly in 1920; they had several children.