James Agar, 1st Viscount Clifden, Irish peer and politician who holds the office of one of the joint Postmasters General of Ireland, is born on March 25, 1723, likely in Gowran Castle, County Kilkenny.

Agar is the second son of Henry Agar, a former Member of Parliament (MP) for Gowran, and Anne Ellis. On March 20, 1760, he marries Lucia Martin, daughter of Colonel John Martin, of Dublin and widow of Henry Boyle-Walsingham. Together they have three children, Henry Welbore Agar-Ellis (b. January 22, 1761), John Ellis (b. December 31, 1763), and Charles Bagnell (b. August 13, 1765).

In addition to being a Member of Parliament (MP) for Gowran, for which he sits three times, from 1753 to 1761, again from 1768 to 1769 and finally from 1776 to 1777, he controls three other borough seats through the strength of his family holdings. Between 1761 and 1776, he represents Kilkenny County and between 1768 and 1769 Thomastown. He holds the post of joint Postmaster General of Ireland between 1784 until 1789 with William Ponsonby, 1st Baron Ponsonby.

Agar is made a Baron Clifden on July 27, 1776, and Viscount Clifden on January 12, 1781, and Baron Mendip on August 13, 1794. He dies on January 1, 1789, when his eldest son becomes the 2nd Viscount Clifden and Baron Mendip. His younger brother is Charles Agar, 1st Earl of Normanton (1736–1809), who becomes the Church of Ireland Archbishop of Dublin.