Viscount Downe is a title that has been created twice in the Peerage of Ireland. The first creation came in 1675 for William Ducie. However, the title became extinct on his death in 1679. The second creation came in 1680 for John Dawnay. He had earlier represented Yorkshire and Pontefract in the English House of Commons. His son, the second Viscount, also represented these constituencies in the House of Commons. His grandson, the third Viscount, sat as a Member of Parliament for Yorkshire but died from wounds received at the Battle of Campen in 1760. He was succeeded by his younger brother, the fourth Viscount, who represented Cirencester and Malton in Parliament.

The Peerage of Ireland consists of those titles of nobility created by the English monarchs in their capacity as Lord or King of Ireland, or later by monarchs of the United Kingdom of Great Britain and Ireland. It is one of the five divisions of Peerages in the United Kingdom. The creation of such titles came to an end in the 19th century. The ranks of the Irish peerage are duke, marquess, earl, viscount and baron. As of 2016, there were 135 titles in the Peerage of Ireland extant: two dukedoms, ten marquessates, 43 earldoms, 28 viscountcies, and 52 baronies. However, these titles have no official recognition in the Republic of Ireland, with Article 40.2 of the Constitution of Ireland forbidding the state conferring titles of nobility and stating that an Irish citizen may not accept titles of nobility or honour except with the prior approval of the Irish government.