Hill, Arthur (1600–63), politician, was second son of Sir Moyses Hill of Hill Hall, Co. Down, and Alice Hill (née McDonnell), related to the future earls of Antrim. Building on the success of his father, who had acquired large estates in eastern Ulster at the expense of the O'Neill and Magennis families, in the 1630s Hill established himself as one of the biggest landowners in Co. Down, with a seat at Kilwarlin, and estates at Iveagh. His political connections included not only such Ulster families as the Chichesters and Conways, but also members of the Dublin administration: in the 1630s he married, successively, the daughter of Lord Chancellor Bolton (qv), and (after her death) the daughter of the future lord justice, Sir William Parsons (qv). On the outbreak of the Irish rebellion of 1641, Hill was thrown into the defence of the local garrisons, despite his lack of military experience. In 1642, when he travelled to Westminster to lobby on behalf of the Ulster settlers, he was made colonel of horse by parliament. In November 1642 and April 1643 Hill attended Charles I in Oxford, in an attempt to persuade the king to support vigorous action against the Irish rebels. Hill's own sympathies probably lay with parliament, but on his return to Ulster he found that the English planters, although rejecting the cessation of arms signed by the marquess of Ormond (qv) and the catholic confederates, were reluctant to take the Scottish covenant and thus signal their loyalty to parliament. It was not until the end of 1644 that Hill and his allies had persuaded parliament of their loyalty, and secured much-needed supplies for the garrison towns.
In the summer of 1645 Hill again crossed to England to advise parliament on the Irish war, and he remained in London as an agent for the Ulster officers until the autumn of 1648. Hill had no qualms about serving the commonwealth after the execution of Charles I. During 1649 and 1650 he acted as a secretary or agent to the council of state's Irish committee, with a salary and attendant clerks. He was able to use this position to extract promises for the repayment of sums he had disbursed in earlier years, including £8,000 for expenses, as well as £5,000 for his military arrears. Returning to Ulster in November 1650, Hill became a revenue commissioner and soon extended his local influence and prestige. He was able to protect former royalists (including Viscount Conway (qv) and Marcus Trevor (qv)) from sequestration; he rebuilt his house at Kilwarlin and began work on Hillsborough Fort; and in August 1654 he was elected for the counties of Antrim, Armagh, and Down in the first protectorate parliament. In the later 1650s Hill remained an influential figure, sitting on the English council's trade committee from January 1656, and advising Henry Cromwell (qv) in Dublin in 1657–8. He also enjoyed personal connections with leading Irish politicians, including Arthur Annesley (qv), Lord Broghill (qv), and Sir Charles Coote (qv). Hill remained aloof from the Dublin coup of December 1659, but supported the convention in early 1660, being elected for Co. Down. In the months before the restoration, he was counted as a man of great political importance, second only to Broghill and Coote.
After the restoration, Hill was loaded with favours. In December 1660, on the duke of Ormond's recommendation, he was granted the constableship of Hillsborough; he was sworn to the Irish privy council in the same month; and he was pardoned, at Coote's behest, in January 1661. In the same year Hill was returned as MP for Co. Down in the Irish parliament. At this time he was active as a trustee for the pre-1649 officers – a concern he shared with his old friend and kinsman, George Rawdon (qv). Like Rawdon, Hill was an enthusiastic supporter of the Church of Ireland, and was on good terms with the new archbishop of Armagh, John Bramhall (qv). Hill died in April 1663. His son and heir by his first marriage, Moyses Hill, died in 1664 and was succeeded by his half-brother, William Hill, whose descendants include the Viscounts Hillsborough and earls of Downshire.