William III (William Henry; Dutch: Willem Hendrik; 4 November 1650 8 March 1702), also widely known as William of Orange, was the sovereign Prince of Orange from birth, Stadtholder of Holland, Zeeland, Utrecht, Guelders, and Overijssel in the Dutch Republic from the 1670s, 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 as "King Billy" in Ireland and Scotland. His victory at the Battle of the Boyne in 1690 is commemorated by Unionists, who display orange colours in his honour. He ruled Britain alongside his wife and cousin Queen Mary II, and popular histories usually refer to their reign as that of "William and Mary".

William was the only child of William II, Prince of Orange, and Mary, Princess Royal, the daughter of Charles I of England, Scotland, and Ireland. His father died a week before his birth, making William III the Prince of Orange from birth. In 1677, he married Mary, the eldest daughter of his maternal uncle James, Duke of York, the younger brother of Charles II of England, Scotland, and Ireland. The Protestant William participated in several wars against the powerful Catholic French ruler Louis XIV in coalition with both Protestant and Catholic powers in Europe. Many Protestants heralded William as a champion of their faith. In 1685, his 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, who feared a revival of Catholicism. Supported by a group of influential British political and religious leaders, William invaded England in what became known as the Glorious Revolution. In 1688, he landed at the south-western English port of Brixham; James was deposed shortly afterward.

William's reputation as a staunch Protestant enabled him and his wife to take power. During the early years of his reign, William was occupied abroad with the Nine Years' War (16881697), leaving Mary to govern Britain alone. She died in 1694. In 1696 the Jacobites, a faction loyal to the deposed James, plotted unsuccessfully to assassinate William and restore James to the throne. William's lack of children and the death in 1700 of his nephew Prince William, Duke of Gloucester, the son of his sister-in-law Anne, threatened the Protestant succession. The danger was averted by placing distant relatives, the Protestant Hanoverians, in line to the throne with the Act of Settlement 1701. Upon his death in 1702, the king was succeeded in Britain by Anne and as titular Prince of Orange by his cousin John William Friso, beginning the Second Stadtholderless period.

The College of William & Mary (also known as William & Mary, W&M, and officially The College of William and Mary in Virginia) is a public research university in Williamsburg, Virginia. Founded in 1693 by letters patent issued by King William III and Queen Mary II, it is the second-oldest institution of higher education in the United States and the ninth-oldest in the English-speaking world.William & Mary educated American presidents Thomas Jefferson, James Monroe, and John Tyler. It also educated other key figures pivotal to the development of the United States, including the first President of the Continental Congress Peyton Randolph, the first U.S. Attorney General Edmund Randolph, the fourth U.S. Supreme Court Chief Justice John Marshall, Speaker of the House of Representatives Henry Clay, Commanding General of the U.S. Army Winfield Scott, sixteen members of the Continental Congress, and four signers of the Declaration of Independence. This earned it the nickname "the Alma Mater of the Nation". A young George Washington also received his surveyor's license at the college in 1749 and he would become the college's first American chancellor in 1788. The position was long held by Bishops of London and Archbishops of Canterbury, though in modern times has been held by U.S. Supreme Court Justices, Cabinet Secretaries, and British Prime Minister Margaret Thatcher. Benjamin Franklin received William & Mary's first honorary degree in 1756.William & Mary is notable for its many firsts in American higher education. The F.H.C. Society, founded in 1750, was the first collegiate fraternity in the United States, and W&M students founded the Phi Beta Kappa academic honor society in 1776, the first Greek-letter fraternity. W&M was also the first school of higher education in the United States to install an honor code of conduct for students, dating back to 1736. It was the first and only American university issued a coat of arms by the College of Arms in London. The establishment of graduate programs in law and medicine in 1779 makes it one of the first universities in the United States. The Marshall–Wythe School of Law is the oldest law school in the United States, and the Sir Christopher Wren Building, attributed to the famed English architect, is the oldest academic building in continuous use in the United States.In addition to its prestigious undergraduate program, W&M is home to several top-ranked graduate programs and four professional schools. In his 1985 book Public Ivies: A Guide to America's Best Public Undergraduate Colleges and Universities, Richard Moll included William & Mary as one of the original eight "Public Ivies". It is classified among "R2: Doctoral Universities – High Research Activity".