Charles II (29 May 1630 – 6 February 1685) was King of Scotland from 1649 until 1651 and King of England, Scotland, and Ireland from the 1660 Restoration of the monarchy until his death in 1685.

Charles II was the eldest surviving child of Charles I of England, Scotland and Ireland and Henrietta Maria of France. After Charles I's execution at Whitehall on 30 January 1649, at the climax of the English Civil War, the Parliament of Scotland proclaimed Charles II king on 5 February 1649. However, England entered the period known as the English Interregnum or the English Commonwealth with a republican government eventually led by Oliver Cromwell. Cromwell defeated Charles II at the Battle of Worcester on 3 September 1651, and Charles fled to mainland Europe. Cromwell became Lord Protector of England, Scotland and Ireland. Charles spent the next nine years in exile in France, the Dutch Republic and the Spanish Netherlands. A political crisis after Cromwell's death in 1658 resulted in the restoration of the monarchy in 1660, and Charles was invited to return to Britain. On 29 May 1660, his 30th birthday, he was received in London to public acclaim.

Charles's English Parliament enacted the Clarendon Code, to shore up the position of the re-established Church of England. Charles acquiesced to these new laws even though he favoured a policy of religious tolerance. The major foreign policy issue of his early reign was the Second Anglo-Dutch War. In 1670, he entered into the Treaty of Dover, an alliance with his cousin, King Louis XIV of France. Louis agreed to aid him in the Third Anglo-Dutch War and pay him a pension, and Charles secretly promised to convert to Catholicism at an unspecified future date. Charles attempted to introduce religious freedom for Catholics and Protestant dissenters with his 1672 Royal Declaration of Indulgence, but the English Parliament forced him to withdraw it. In 1679, Titus Oates's fabrication of a supposed Popish Plot sparked the Exclusion Crisis when it was revealed that Charles's brother and heir presumptive, James, Duke of York, had become a Catholic. The crisis saw the birth of the pro-exclusion Whig and anti-exclusion Tory parties. Charles sided with the Tories and, after the discovery of the Rye House Plot to murder Charles and James in 1683, some Whig leaders were executed or forced into exile. Charles dissolved the English Parliament in 1681 and ruled alone until his death in 1685.

A patron of the arts and sciences, Charles became known for his affability and friendliness, and for allowing his subjects easy access to his person. But he also showed an almost impenetrable reserve, especially concerning his political agendas. His court gained a reputation for moral laxity. Charles's marriage to Catherine of Braganza produced no surviving children, but the king acknowledged at least 12 illegitimate children by various mistresses. He was succeeded by his brother James.

Charles was born at St James's Palace on 29 May 1630. He was the eldest surviving son of Charles I, king of England, Scotland and Ireland, and his wife Henrietta Maria of France, sister of King Louis XIII. Charles was their second child (the first being a son born about a year before, who had died within a day). He was baptised on 27 June in the Chapel Royal by William Laud, a future archbishop of Canterbury, and during his infancy was supervised by the Protestant Countess of Dorset. His godparents included his maternal uncle Louis XIII and maternal grandmother, Marie de' Medici, the Dowager Queen of France, both of whom were Catholics. At birth, Charles automatically became Duke of Cornwall and Duke of Rothesay, and the possessor of several other associated titles. At or around his eighth birthday, he was designated Prince of Wales, though he was never formally invested.

In August 1642, the long-running dispute between Charles I and Parliament culminated in the outbreak of the First English Civil War. In October, Prince Charles and his younger brother James were present at the Battle of Edgehill and spent the next two years based in the Royalist capital of Oxford. In January 1645, Charles was given his own Council and made titular head of Royalist forces in the West Country. By spring 1646, most of the region had been occupied by Parliamentarian forces and Charles went into exile to avoid capture. From Falmouth, he went first to the Isles of Scilly, then to Jersey, and finally to France, where his mother was already living under the protection of his first cousin, the eight-year-old Louis XIV. Charles I surrendered into captivity in May 1646.

During the Second English Civil War in 1648, Charles moved to The Hague, where his sister Mary and his brother-in-law William II, Prince of Orange, seemed more likely to provide substantial aid to the Royalist cause than his mother's French relations. Although part of the Parliamentarian fleet defected, it did not reach Scotland in time to join up with the Royalist Engager army led by the Duke of Hamilton before it was defeated at Preston by the New Model Army.

At The Hague, Charles had a brief affair with Lucy Walter, who later falsely claimed that they had secretly married. Her son, James Crofts (afterwards Duke of Monmouth and Duke of Buccleuch), was one of Charles's many illegitimate children who became prominent in British society. Despite his son's diplomatic efforts to save him, the execution of Charles I took place in January 1649, and England became a republic. On 5 February, the Covenanter Parliament of Scotland proclaimed Charles II as "King of Great Britain, France and Ireland" at the Mercat Cross, Edinburgh, but refused to allow him to enter Scotland unless he agreed to establish Presbyterianism as the state religion in all three of his kingdoms.