Mary II (30 April 1662 – 28 December 1694) was Queen of England, Scotland, and Ireland, co-reigning with her husband, William III & II, from 1689 until her death in 1694.

Mary was the eldest daughter of James, Duke of York, and his first wife Anne Hyde. Mary and her sister Anne were raised as Anglicans at the behest of their uncle, King Charles II, although their parents both converted to Roman Catholicism. Charles lacked legitimate children, making Mary second in the line of succession. She married her Protestant first cousin, William of Orange, in 1677. Charles died in 1685 and James took the throne, making Mary heir presumptive. James's attempts at rule by decree and the birth of his son from a second marriage, James Francis Edward, led to his deposition in the Glorious Revolution of 1688 and the adoption of the English Bill of Rights.

William and Mary became king and queen regnant. Mary mostly deferred to William, a renowned military leader and principal opponent of Louis XIV, when he was in England. She did, however, act alone when William was engaged in military campaigns abroad, proving herself to be a powerful, firm, and effective ruler. Mary's death from smallpox at the age of 32 left William as sole ruler until his death in 1702, when he was succeeded by Mary's sister, Anne.