James Hamilton, 1st Earl of Arran and 2nd Lord Hamilton (c. 1475 – 1529) was a Scottish nobleman, naval commander and first cousin of James IV of Scotland. He also served as the 9th Lord High Admiral of Scotland.
 He was the elder of two sons of James Hamilton, 1st Lord Hamilton, and his wife, Mary Stewart, Countess of Arran. Mary was a daughter of King James II of Scotland and his Queen consort Mary of Guelders, and a sister of King James III of Scotland.
 Hamilton succeeded to his father's lordship, inheriting his lands when his father died in 1479. In 1489 his first cousin King James IV made him Sheriff of Lanark, a position his father had previously held, and a Scottish Privy Counsellor. By 28 April 1490 he was married to Elizabeth Home, daughter of Alexander Home, 2nd Lord Home.
 Between April and August 1502, Hamilton commanded a naval fleet sent to help King Hans of Denmark, James IV's uncle, defeat a Swedish-Norwegian rebellion. He negotiated James's marriage to Margaret Tudor and was present at the wedding on 8 August 1503. On the same day Lord Hamilton was created Earl of Arran, with the formal grant three days later, "for his nearness of blood" and his services at the time of the marriage. He was appointed Lieutenant General of Scotland and in May 1504 commanded a naval expedition to suppress an uprising in the Western Isles.
 In September 1507, James IV sent Hamilton as his ambassador on a diplomatic mission to the court of Louis XII of France. When returning in early 1508, he was briefly detained in the Kingdom of England by Henry VII, who was suspicious of a renewal of the Auld Alliance between Scotland and France.
 When Henry VIII of England joined the War of the League of Cambrai by invading France in 1513, Scotland came under pressure to support France against England. Hamilton was given command of the Scottish naval fleet. He first sailed to Ulster and attacked Carrickfergus, the main English stronghold there. The fleet then sailed to France, arriving there in September 1513, too late to be much help as the Scottish army had been defeated at the Battle of Flodden in England on 9 September, with James IV being killed in battle.
 During the minority of King James V, Hamilton opposed Archibald Douglas, 6th Earl of Angus and the English party. He plotted against the Regent John Stewart, 2nd Duke of Albany, and was president of the council of regency during Albany's absence in France from 1517 to 1520. The same year he led an expedition to the border to punish the murderers of the French knight Antoine d'Arces ("De la Bastie").
 He was defeated in an attempt to overpower Angus in the streets of Edinburgh in 1520, a riot known as "Cleanse the Causeway". He was again a member of the council of regency in 1522 and Lieutenant of the South. He joined the Queen Dowager Margaret Tudor in ousting Albany and proclaiming James V in 1524.
 In the same year, Hamilton was compelled by Henry VIII of England to readmit Angus to the council. He supported Angus against John Stewart, 3rd Earl of Lennox in 1526 at the Battle of Linlithgow Bridge, but on the escape of James V from the Douglases, Hamilton received Bothwell from Angus's forfeited estates.
 James Hamilton was married firstly, around 1490, to Elizabeth Home, daughter of Alexander Home, 2nd Lord Home by his second wife, Nichola Ker. The marriage was dissolved in 1506, when it was found that her first husband Thomas Hay, a son of John Hay, 1st Lord Hay of Yester, was still alive at the time of the wedding.
 In November 1504, Hamilton had been granted a divorce from Elizabeth Home on the grounds that she had previously been married to Thomas Hay. Hay had apparently left the country and was thought to be dead when Hamilton married Home, in or before 1490, but in fact he did not die until 1491 or later. This award of divorce was repeated in 1510, suggesting that Hamilton had continued living with her, after 1504, and was held by some to undermine the dissolution of the first marriage as invalid. It is likely that the real motive for divorcing Elizabeth was that she had not born any children, and that Hamilton wanted a legitimate heir; he already had several illegitimate children, his eldest illegitimate son being James Hamilton of Finnart. The complicated legal issues of the first marriage would continue to trouble his heir, whose legitimacy was questioned by his rivals in 1543.
 Hamilton was married secondly, in November 1516, to Janet Bethune, daughter of Sir David Betoun of Creich, and widow of Sir Robert Livingstone of Easter Wemyss, who had been killed at the Battle of Flodden. Arran and Janet Bethune had at least four children:
 Hamilton had further illegitimate issue.
 Children of James Hamilton and his mistress, Beatrix Drummond, daughter of John Drummond, 1st Lord Drummond and Lady Elizabeth Lindsay: