Mary, Queen of Scots (8 December 1542 – 8 February 1587), also known as Mary Stuart or Mary I of Scotland, was Queen of Scotland from 14 December 1542 until her forced abdication on 24 July 1567.

The only surviving legitimate child of James V of Scotland, Mary was six days old when her father died and she inherited the throne. During her childhood, Scotland was governed by regents, first by the heir to the throne, James Hamilton, Earl of Arran, and then by her mother, Mary of Guise. In 1548, she was betrothed to Francis, the Dauphin of France, and was sent to be brought up in France, where she would be safe from invading English forces during the Rough Wooing. Mary married Francis in 1558, becoming queen consort of France from his accession in 1559 until his death in December 1560. Widowed, Mary returned to Scotland in August 1561. The tense religious and political climate following the Scottish Reformation that Mary encountered on her return to Scotland was further agitated by prominent Scots such as John Knox, who openly questioned whether her subjects had a duty to obey her. The early years of her personal rule were marked by pragmatism, tolerance, and moderation. She issued a proclamation accepting the religious settlement in Scotland as she had found it upon her return, retained advisers such as James Stewart, Earl of Moray (her illegitimate half-brother), and William Maitland of Lethington, and governed as the Catholic monarch of a Protestant kingdom.

In 1565, Mary married her half-cousin Henry Stuart, Lord Darnley; they had a son, James. Their marriage soured after Darnley orchestrated the murder of Mary's Italian secretary and close friend David Rizzio. In February 1567, Darnley's residence was destroyed by an explosion, and he was found murdered in the nearby garden. James Hepburn, 4th Earl of Bothwell, was generally believed to have orchestrated Darnley's death, but he was acquitted of the charge in April 1567 and in the following month he married Mary. Following an uprising against the couple, Mary was imprisoned in Lochleven Castle. In July 1567, she was forced to abdicate in favour of her one-year-old son James VI. After an unsuccessful attempt to regain the throne, she fled southward seeking the protection of her first cousin once removed, Elizabeth I of England.

As a great-granddaughter of Henry VII of England, Mary had once claimed Elizabeth's throne as her own and was considered the legitimate sovereign of England by many English Catholics, including participants in a rebellion known as the Rising of the North. Perceiving Mary as a threat, Elizabeth had her confined in various castles and manor houses in the interior of England. After eighteen and a half years in captivity, Mary was found guilty of plotting to assassinate Elizabeth in 1586 and was beheaded the following year at Fotheringhay Castle. Mary's life and execution established her in popular culture as a romanticised historical character.

Mary was born on 8 December 1542 at Linlithgow Palace, Scotland, to King James V and his French second wife, Mary of Guise. She was said to have been born prematurely and was the only legitimate child of James to survive him. She was the great-granddaughter of King Henry VII of England through her paternal grandmother, Margaret Tudor. Margaret was Henry VIII's older sister so Mary was Henry VIII's great-niece. On 14 December, six days after her birth, she became Queen of Scotland when her father died, perhaps from the effects of a nervous collapse following the Battle of Solway Moss or from drinking contaminated water while on campaign.

A popular tale, first recorded by John Knox, states that James, upon hearing on his deathbed that his wife had given birth to a daughter, ruefully exclaimed, "It cam wi' a lass and it will gang wi' a lass!" His House of Stuart had gained the throne of Scotland in the 14th century through "a lass"—via the marriage of Marjorie Bruce, daughter of Robert the Bruce, to Walter Stewart, 6th High Steward of Scotland—and it would be lost from his family "wi' a lass". This legendary statement came true much later—not through Mary, but through her great-great-granddaughter Anne, Queen of Great Britain.

Mary was christened at the nearby Church of St Michael shortly after she was born. Rumours spread that she was weak and frail, but an English diplomat, Ralph Sadler, saw the infant at Linlithgow Palace in March 1543, unwrapped by her nurse Jean Sinclair, and wrote, "it is as goodly a child as I have seen of her age, and as like to live."

As Mary was an infant when she inherited the throne, Scotland was ruled by regents until she became an adult. From the outset, there were two claims to the regency: one from the Catholic Cardinal Beaton, and the other from the Protestant Earl of Arran, who was next in line to the throne. Beaton's claim was based on a version of the king's will that his opponents dismissed as a forgery. Arran, with the support of his friends and relations, became the regent until 1554 when Mary's mother managed to remove and succeed him.