Pierre Lagaillarde was a French politician, and a founder of the Organisation armée secrète.
Lagaillarde was a lawyer at Blida in Algeria, a reserve officer of the paratroopers, and an elected deputy of Algiers. He took the presidency of the Association générale des étudiants d'Alger in 1957, and also took part in the Alger insurrection of May 1958, which brought Charles de Gaulle back to power. Lagaillarde was member of the Comité de salut public which opposed Algerian independence, and occupied the Gouvernement général de l'Algérie. In November 1958, he was on the electoral list Algérie française, and then became a leader of the insurrection during the week of the barricades in January 1960.
Lagaillarde was then detained in la Santé in Paris, and took advantage of his parole to escape to Spain, where he joined Raoul Salan and founded the Organisation armée secrète on 3 December 1960. Deprived of his immunity as a deputy, he was sentenced in absentia to ten years of prison in March 1961.
In October 1961 he was arrested in Madrid, along with the Italian neofascist Guido Giannettini. Franco then exiled him to the Canary Islands.