Isidore Isou (1925 Botoșani, Romania – 2007 Paris, France) was a Romanian-born French poet, dramaturge, visual artist, and film director; a prominent member of the avant-garde, he influenced many Fluxus artists. Given his Jewish origins and the repressive regime of Ion Antonescu in Romania, Isou fled to Paris near the end of World War II. Here, he began working as a journalist, co-founding Da, an underground magazine published in collaboration with Serge Moscovici. With his friend and collaborator Gabriel Pommerand, Isou co-founded Lettrism, a literary and artistic movement based on the sign, advocating the destruction of words in favor of letters. In 1946, Isou organized his first Lettrist manifestation in Paris, stating that Dada had died and that Lettrism had taken its place. The following year, he published Introduction à une nouvelle poésie et à une nouvelle musique, containing the first manifesto of Lettrist poetry. The Lettrist poem consists of a text script for a vocal performance composed of meaningless sounds transcribed through letters. On the visual side, it is presented using all possible means of notation: graphic, stenographic, cryptographic, algebraic, numerical, and musical. A compulsive writer, Isou drafted hundreds of works concerned not only with the visual arts but also with economics, mathematics, sociology, and psychology. In 1987, Isou participated in documenta 8 in Kassel. Isou’s work and the history of Lettrism are the focus of numerous publications and are included in the collections of the Museo Reina Sofía in Madrid, the MACBA – Museu d’Art Contemporani de Barcelona, and the Centre Pompidou in Paris, where a major retrospective took place in 2019.