Gerard FitzGerald, 9th Earl of Kildare, was a leading figure in 16th-century Irish History. In 1513 he inherited the title of Earl of Kildare and position of Lord Deputy of Ireland from his father.

Duke of Leinster is a title in the Peerage of Ireland and the premier dukedom in that peerage. The subsidiary titles of the Duke of Leinster are: Marquess of Kildare (1761), Earl of Kildare (1316), Earl of Offaly (1761), Viscount Leinster, of Taplow in the County of Buckingham (1747), Baron of Offaly, Baron Offaly (1620) and Baron Kildare, of Kildare in the County of Kildare (1870). The viscounty of Leinster is in the Peerage of Great Britain, the barony of Kildare in the Peerage of the United Kingdom, and all other titles in the Peerage of Ireland. The courtesy title of the eldest son and heir of the Duke of Leinster is Marquess of Kildare. The Duke of Leinster is the head of the House of Kildare.