Viscount Clifden, of Gowran in the County of Kilkenny, Ireland, was a title in the Peerage of Ireland. It was created on 12 January 1781 for James Agar, 1st Baron Clifden. He had already been created Baron Clifden, of Gowran in the County of Kilkenny, in 1776, also in the Peerage of Ireland. The Viscounts also held the titles of Baron Mendip in the Peerage of Great Britain from 1802 to 1974 (a title which is still extant and now held by the Earl of Normanton) and Baron Dover from 1836 to 1899, when this title became extinct, and Baron Robartes from 1899 to 1974, when this title became extinct, the two latter titles which were in the Peerage of the United Kingdom. The interrelated histories of the peerages follows below.
James Agar, 1st Viscount Clifden was the son of Henry Agar of Gowran Castle and the elder brother of Charles Agar, 1st Earl of Normanton. His mother was Anne Ellis, daughter of Welbore Ellis, Bishop of Meath, and sister of the politician Welbore Ellis, who in 1794 was created Baron Mendip in the Peerage of Great Britain with remainder to his three nephews Lord Clifden, the future Lord Normanton and another brother of theirs. Lord Clifden was succeeded by his son, the second Viscount. He represented County Kilkenny in the Irish House of Commons and Heytesbury in the British House of Commons.