Marquess of Ely, of the County of Wexford, is a title in the Peerage of Ireland. It was created in 1800 for Charles Loftus, 1st Earl of Ely. He was born Charles Tottenham, the son of Sir John Tottenham, 1st Baronet, who had been created a baronet, of Tottenham Green in the County of Wexford, in the Baronetage of Ireland in 1780, by Elizabeth, daughter of Nicholas Loftus, 1st Viscount Loftus, sister and heiress of Henry Loftus, 1st Earl of Ely. In 1783 he succeeded to the Loftus estates on the death of his maternal uncle the Earl of Ely and assumed the same year by Royal licence the surname of Loftus in lieu of his patronymic. In 1785 he was raised to the Peerage of Ireland as Baron Loftus, of Loftus Hall in the County of Wexford. It was sold by the family in 1917 and is today owned by the Quigley family.

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.