Carlism (Basque: Karlismo; Catalan: Carlisme; Galician: Carlismo; Spanish: Carlismo) is a Traditionalist and Legitimist political movement in Spain aimed at establishing an alternative branch of the Bourbon dynasty – one descended from Don Carlos, Count of Molina (1788–1855) – on the Spanish throne.

The movement was founded in consequence of a dispute over the succession laws and widespread dissatisfaction with the Alfonsine line of the House of Bourbon. It was at its strongest in the 1830s but experienced a revival following Spain's defeat in the Spanish–American War in 1898, when Spain lost its last remaining significant overseas territories of the Philippines, Cuba, Guam, and Puerto Rico to the United States.

Carlism was a significant force in Spanish politics from 1833 until the end of the Francoist regime in 1975. In this capacity, it was the cause of the Carlist Wars of the 19th century and an important factor in the Spanish Civil War in the 1930s. Today, Carlists are a minor party.

Objectively considered, Carlism appears as a political movement. It arose under the protection of a dynastic flag that proclaimed itself "legitimist", and that rose to the death of Ferdinand VII, in the year 1833, with enough echo and popular roots, [...] they distinguish in it three cardinal bases that define it:
a) A dynastic flag: that of legitimacy.
b) A historical continuity: that of Las Españas.
c) And a legal-political doctrine: the traditionalist.