Boyle, Henry (c.1668–1725), 1st Baron Carleton, politician, was the son of Charles Boyle, Viscount Dungarvan (Ireland) and Baron Clifford (England), and his first wife, Jane, daughter of William Seymour, 2nd duke of Somerset. His grandfather was Richard Boyle (qv), 2nd earl of Cork and 1st earl of Burlington, and he was the younger brother of Charles Boyle (qv), 3rd earl of Cork and 2nd earl of Burlington. Educated at Westminster, he served as a cornet in the Queen's Horse (1685–8). It is probable that he secured his commission through the offices of his uncle Laurence Hyde (qv), earl of Rochester. In November 1688 he went over to William of Orange (qv) and served him as a major in the 2nd Life Guards. He served as MP for Tamworth in the convention parliament in 1689, but failed to find a seat at Westminster in the 1690 election. Instead he travelled to Ireland to manage his grandfather's extensive estates in Co. Cork and Co. Waterford. In 1692 he was elected to the Irish house of commons, where he represented Co. Cork. Despite his relative youth he was prominent in the short-lived 1692 parliament, acting as the chairman of the supply committee.
He appears to have been the Henry Boyle returned for Youghal in 1695. Certainly Alan Brodrick (qv) mentioned Lord Clifford's brother Harry as a possible candidate for the speakership of the Irish house of commons in that year. It is difficult to know how serious this bid was; certainly Boyle was closely connected to the lord deputy, Henry Capel (qv), who attempted to nominate him to the Irish privy council in the same year. In 1697 Boyle was mentioned as a possible lord justice, but this came to nothing, possibly because of opposition from the Brodrick interest in Ireland, or because of Boyle's reluctance to leave England.
Boyle, much to his grandfather Burlington's disappointment, chose to make his career in England. In November 1692 he was returned to the English house of commons for Cambridge University, where his uncle, the duke of Somerset, was chancellor. In order to assist his election he was hastily admitted to Trinity College, Cambridge, in November 1692, from where he graduated with an MA in the following year. Boyle continued to represent the university constituency until 1705, when he was elected for Westminster, a seat he held until 1710. During his first four or five years in parliament he was an increasingly prominent member of the ‘country’ opposition, but in the winter of 1697–8 he crossed over to the court party, where his talents were quickly rewarded. He served as a lord of the treasury 1699–1701, and as chancellor of the exchequer 1701–8. During this time he was seen as a strong whig. On Robert Harley's dismissal in 1708, Boyle became secretary of state for the northern department. He also acted as one of the managers of the Sacheverell trial in 1709.
On the tory victory in 1710, he was replaced as secretary by Henry St John (later Lord Bolingbroke). Boyle retired from active politics in 1710, having little desire to get involved in the intense party strife that characterised the remaining years of Queen Anne's reign. After the Hanoverian succession, Boyle was raised to the English peerage (19 October 1714) as Baron Carleton of Carleton, Yorkshire, and served as lord president of the council in Walpole's administration (1721–5). He died unmarried 14 March 1725, at his London home, Carleton House, later home to successive princes of Wales. He left a fortune valued at over £27,000 as well as substantial estates in Oxfordshire, Wiltshire, and Surrey. He was buried in the family vault at Londesborough, Yorkshire.