A Tory (/ˈtɔːri/) is an individual who supports a political philosophy known as Toryism, based on a British version of traditionalist conservatism which upholds the established social order as it has evolved through the history of Great Britain. The Tory ethos has been summed up with the phrase "God, King (or Queen) and Country". Tories are monarchists, were historically of a high church Anglican religious heritage, and were opposed to the liberalism of the Whig party.

The philosophy originates from the Cavaliers, a royalist faction which supported the House of Stuart during the Wars of the Three Kingdoms. The Tories, a British political party which emerged during the late 17th century, was a reaction to the Whig-controlled Parliaments that succeeded the Cavalier Parliament. As a political term, Tory (a word of Irish origin) was first used during the Exclusion Crisis of 1678–1681.

It also has exponents in other parts of the former British Empire, such as the Loyalists of British America, who opposed secession during the American War of Independence. Loyalists who fled to the Canadas at the end of the conflict, known as the United Empire Loyalists, formed the support base for political cliques in Upper and Lower Canada. Toryism remains prominent in the politics of Canada and the United Kingdom. The British Conservative Party and Conservative Party of Canada, and their supporters, continue to be referred to as Tories. Adherents to traditional Toryism in contemporary times are referred to as High Tories, who typically defend the ideas of hierarchy, natural order, and aristocracy.

The word Tory derives from the Irish tóraí, meaning "outlaw" (literally "pursuer"). It entered the English language in the 17th century, when it was used to describe Irish outlaws who survived by committing acts of robbery and plunder against English settlers. Later, it came to denote any Catholic or Royalist who had taken up arms against the English government.

The word entered English politics during the Exclusion Crisis, emerging as a pejorative term for supporters of the Duke of York and his hereditary right to inherit the throne despite his Catholic religion. According to Daniel Defoe, it was popularised by Titus Oates, who once received a warning that a group of Irish Tories intended to assassinate him. Following this incident, Oates "could never hear any man [...] talk against the plot, or against the witnesses, but he thought he was one of these tories, and call'd almost every man a tory that oppos'd him in discourse; till at last the word tory became popular, and it stuck so close to the [Yorkist] party in all their bloody proceedings that they had no way to get it off".

Although both Tory and Whig originated as pejoratives, they soon became neutral terms for the two major factions in British politics. The suffix -ism was added to make Whiggism and Toryism, meaning the principles and methods of each faction.

During the American Revolution, the term Tory was used interchangeably with the term "Loyalist" in the Thirteen Colonies to refer to colonists who remained loyal to the Crown during the conflict. The term contrasts the colloquial term used to describe supporters of the revolution, "Patriots" or "Whigs".

Towards the end of Charles II's reign (1660–1685) there was some debate about whether his brother, James, Duke of York, should be allowed to accede to the throne because of James's Catholicism. "Whigs", originally a reference to Scottish cattle-drovers (stereotypically radical anti-Catholic Covenanters), was the abusive term directed at those who wanted to exclude James on the grounds that he was a Catholic. Those who were not prepared to exclude James were labelled "Abhorrers" and later "Tories". Titus Oates applied the term Tory, which then signified an Irish robber, to those who would not believe in his Popish Plot and the name gradually became extended to all who were supposed to have sympathy with the Catholic Duke of York.