Youenn Drezen (14 September 1899 – 17 February 1972) is the Breton language name of Yves Le Drézen, a Breton nationalist writer and activist. He is also known as Corentin Cariou and Tin Gariou.
He was born in Pont-l'Abbé, Finistère into a poor family. His father died in 1911, leaving eight children to be raised by his young widow. Taken in by Catholic missionaries, he moved to Spain as a seminarian, living in the Basque region and then Castille. He met Jakez Riou and while conducting literary, scientific and religious studies, they explored the literary potential of the Breton language, aspiring to give it a refined form unsullied by convention.
Having abandoned his religious training, he met, while on military service in Rennes, officials of the nationalist group Unvaniezh Yaouankiz Breiz, which led to the publication of his first article in support of Breton nationalism in the journal Breiz Atao.
In 1924, he became a journalist with the Courrier du Finistère. He participated in the Quimper Pan-Celtic Congress of 1924, with François Debeauvais, Yann Sohier, Jakez Riou, Abeozen, and Marcel Guieysse, under the banner of Breiz Atao. He later worked for Gwalarn, the literary magazine founded in 1922 by Roparz Hemon and Olier Mordrel, where he established himself by publishing Breton translations from Spanish (Calderon) and ancient Greek (Aeschylus). He also published his own poetry, notably Nozvez arkus e beg an enezenn (Night Watch at the Edge of the Island), written in memory of Jakez Riou in 1938.
He also translated books for children, for example Beatrix Potter. These were published by Gwalarn, and were distributed free in schools to children who had participated in essay competitions in the Breton language.
Drezen's translations led to a full-time career as a writer. He produced a rich and varied oeuvre of poems, novels and plays, always written entirely in Breton. Some novels have been translated into French (by Pêr-Jakez Helias among others). He is considered one of the best writers in Breton, because he knew how to mix vivid expression with a quest for literary perfection, sometimes through euphony.