A double-barrelled name is a family name with two parts, which may or may not be joined with a hyphen, for example Bowes-Lyon. The term is an analogy with double-barrelled shotgun .

Double barrelled names may be formed for a variety of reasons. Some are formed when women add their husband's surname to their own family name upon marriage, thus forming a new two-part surname, or when children are given surnames combining those of both parents. Double-barrelled names may also be used by children who are not brought up by their birth-parents to combine the surname of a birth-parent with that of an adoptive parent, or the surname of their biological father with that of a stepfather.

Double-barrelled names are sometimes adopted to avoid having a 'common' surname. Because of this, and because many upper class families have multi-part surnames, it is often assumed that double-barrelled names signify a certain pretentiousness or snobbishness on the part of the bearer. In fact, as we have seen, double-barrelled names may be adopted for a number of quite different reasons.

A few upper-class families (e.g. Anstruther-Gough-Calthorpe; Cave-Brown-Cave; Elliot-Murray-Kynynmound; Heathcote-Drummond-Willoughby; Vane-Tempest-Stewart) have triple-barrelled surnames (created when a double-barrelled husband married a single-barrelled wife, or vice versa). Nowadays such names are almost always abbreviated in everyday use to a single- or double-barrelled version. There are even a few quadruple-barrelled surnames (e.g. Stirling-Home-Drummond-Moray; Plunkett-Ernle-Erle-Drax) and the surname of the extinct family of the Dukes of Buckingham and Chandos was the quintuple-barrelled Temple-Nugent-Brydges-Chandos-Grenville.

Many double-barrelled names are written without a hyphen, e.g. John Maynard Smith, Iain Duncan Smith. (This can cause confusion as to whether the surname is double-barrelled or not.) One notable current example of this form of double-barrelling is Andrew Lloyd Webber, whose surname is now Lloyd Webber (not just Webber), though it used to be written with a hyphen, and so, confusingly, his peerage title is Baron Lloyd-Webber, with a hyphen. Notable persons with unhyphenated double-barrelled names include two former British Prime Ministers, David Lloyd George and Andrew Bonar Law, and the composer Ralph Vaughan Williams.