Esclarmonde of Foix (French: Esclarmonde de Foix; Occitan: Esclarmonda de Fois), was a prominent figure associated with Catharism in thirteenth century Occitania (in the south of modern-day France).
Esclarmonde settled in Pamiers and was probably involved in an initiative to rebuild the fortress of the Château de Montségur.
The following year, in 1208, Pope Innocent III launched the Albigensian Crusade against the Cathars after the murder of his delegate Pierre de Castelnau.
For the Catholics, she spread heresy in the country and forced people to adopt the rules of the Cathars.
The significance of her name's meaning, i.e. "clarity of the world", is explored in several medieval epic poems including one referred to as "Esclaramonde", by Bertran de Born, and in "Parzival" by Wolfram von Eschenbach.