Earl of Mount Alexander was a title in the Peerage of Ireland

Peerage of Ireland

The Peerage of Ireland is the term used for those titles of nobility created by the English and later British monarchs of Ireland in their capacity as Lord or King of Ireland. The creation of such titles came to an end in the 19th century. The ranks of the Irish peerage are Duke, Marquess, Earl,...

. It was created in 1661 for Hugh Montgomery, 3rd Viscount Montgomery. He was the grandson of Hugh Montgomery, known as one of the "founding fathers" of the Ulster Scots, who was raised to the Peerage of Ireland as Viscount Montgomery, of the Great Ardes, in 1622. The fourth Earl represented Antrim Borough in the Irish House of Commons

Irish House of Commons

The Irish House of Commons was the lower house of the Parliament of Ireland, that existed from 1297 until 1800. The upper house was the House of Lords...

. The titles became extinct on the death of the fifth Earl in 1757.

Viscounts Montgomery (1622)

• Hugh Montgomery, 1st Viscount Montgomery (1560–1636)
• Hugh Montgomery, 2nd Viscount Montgomery (1616–1642)
• Hugh Montgomery, 3rd Viscount Montgomery (c. 1625–1663) (created Earl of Mount Alexander in 1661)

Earls of Mount Alexander (1661)

• Hugh Montgomery, 1st Earl of Mount Alexander
  Hugh Montgomery, 1st Earl of Mount Alexander
  Hugh Montgomery, 1st Earl of Mount Alexander , known as The Viscount Montgomery from 1642 to 1661, was an Irish peer. He was appointed to command his father's regiment, 1642. He was commander-in-chief of the Royalist army in Ulster in 1649 and seized successively Belfast, Antrim, and Carrickfergus...
  
   (c.1625–1663)
• Hugh Montgomery, 2nd Earl of Mount Alexander (1651–1717)
• Henry Montgomery, 3rd Earl of Mount Alexander (c. 1652–1731)
• Hugh Montgomery, 4th Earl of Mount Alexander (d. 1745)
• Thomas Montgomery, 5th Earl of Mount Alexander (d. 1757)