William III (Dutch: Willem; 4 November 1650 – 8 March 1702), also widely known as William of Orange, was sovereign Prince of Orange from birth, Stadtholder of Holland, Zeeland, Utrecht, Gelderland and Overijssel in the Dutch Republic from 1672 and King of England, Ireland and Scotland from 1689 until his death in 1702. As King of Scotland, he is known as William II. He is sometimes informally known in Northern Ireland and Scotland as "King Billy".
William inherited the principality of Orange from his father, William II, who died a week before William's birth. His mother, Mary, was the daughter of King Charles I of England. In 1677, William married his fifteen-year-old first cousin, Mary, the daughter of his maternal uncle James, Duke of York.
A Protestant, William participated in several wars against the powerful Catholic King of France, Louis XIV, in coalition with Protestant and Catholic powers in Europe. Many Protestants heralded him as a champion of their faith. In 1685, William's Catholic uncle and father-in-law, James, became king of England, Scotland and Ireland. James's reign was unpopular with the Protestant majority in Britain. William, supported by a group of influential British political and religious leaders, invaded England in what became known as the Glorious Revolution. On 5 November 1688, he landed at the southern English port of Brixham. James was deposed and William and his wife became joint sovereigns in his place. William and Mary reigned together until Mary's death on 28 December 1694, after which William ruled as sole monarch.
William's reputation as a staunch Protestant enabled him to take power in Britain when many were fearful of a revival of Catholicism under James. William's victory at the Battle of the Boyne in 1690 is still commemorated by loyalists in Northern Ireland and Scotland. His reign in Britain marked the beginning of the transition from the personal rule of the Stuarts to the more Parliament-centred rule of the House of Hanover.