Richard Butler, 1st Viscount Mountgarret (1500 – 20 May 1571) was the son of Piers Butler, 8th Earl of Ormond and Lady Margaret Fitzgerald. He married his first cousin Eleanor Butler, daughter of Theobald Butler of Polestown, the illegitimate brother of the 8th Earl of Ormond. He was created 1st Viscount Mountgarret in 1550.
He was described as a "Knight of goodly personage, and as comely a man as could be seen", and performed services to the Crown of England. As recompense, the Lords of the council, in their letter to the Deputy Lieutenant, St. Leger, dated at Windsor 5 August 1550, transmitted the directions of King Edward VI of England to create him Viscount Mountgarret. This was done by patent, bearing date at Dublin 23 October.
In the reigns of Edward VI and Queen Mary, he was keeper of the castle of Ferns. On 20 March 1558 he joined in a commission of martial law with Sir Nicholas Devereux for the territories of Fassaghbentry and LeMoroe's country. On 13 April 1559 was in two several commissions "for the preservation of the peace in the counties of Kilkenny, Tipperary and Wexford",. during the absence of the Deputy Lieutenant, Lord Sussex, in the north, uon his expedition against Shane O'Neill. On the following 12 January he was present in the Parliament.
He died in 1571 and was buried alongside his ancestors in St. Canice's Cathedral, Kilkenny city.
His first wife was Eleanor, daughter of Theobald Butler of Nechum (or Polestown) in the county of Kilkenny, by whom he had Edmund, his successor.
His second marriage was to Catharine, daughter and heir to Peter Barnewall of Stackallan in Meath, and by her he had a son Barnewall, who died unmarried.
His third marriage was in 1541 to Anne, daughter of John Plunket, Lord Killeen, from whom he was divorced in the first year of their marriage.
Having issue in all five sons and four daughters, viz.