Baron Castlemaine

Baron Castlemaine, of Moydrum in the County of Westmeath, is a title in the Peerage of Ireland. It was created in 1812 for William Handcock, with remainder to his younger brother Richard Handcock. Handcock represented Athlone in Parliament and also served as Governor of County Westmeath. In 1822 he was further honoured when he was made Viscount Castlemaine in the Peerage of Ireland, with remainder to the heirs male of his body.

Moydrum Castle, the former seat of the Handcock family

On Lord Castlemaine's death the viscountcy became extinct as he died childless, but he was succeeded in the barony according to the special remainder by his brother Richard, the second Baron. He also represented Athlone in Parliament. His son, the third Baron, was also Member of Parliament for Athlone and sat in the House of Lords as an Irish Representative Peer from 1841 to 1869. He was succeeded by his eldest son, the fourth Baron. He served as an Irish Representative Peer from 1874 to 1892 and was Lord Lieutenant of County Westmeath from 1888 to 1892.

On his death the title passed to his son, the fifth Baron. He was an Irish Representative Peer from 1898 to 1937 and served as Lord Lieutenant of County Westmeath from 1899 to 1922. On the death of his younger brother, the sixth Baron, the line of the eldest son of the third Baron failed. He was succeeded by his first cousin once removed, the seventh Baron. He was the grandson of the Hon. Robert John Handcock, second son of the third Baron. As of 2014 the title is held by his son, the eighth Baron, who succeeded in 1973.

The family seat was Moydrum Castle, near Athlone, County Westmeath.