Joseph Déjacque (French: [de?ak]; December 27, 1821, Paris – 1864, Paris) was a French early anarcho-communist poet, philosopher and writer.
Déjacque was the first recorded person to employ the term "libertarian" (French: libertaire) for himself in a political sense in a letter written in 1857, criticizing Pierre-Joseph Proudhon for his sexist views on women, his support of individual ownership of the product of labor and of a market economy, saying that "it is not the product of his or her labor that the worker has a right to, but to the satisfaction of his or her needs, whatever may be their nature".