José Luis Álvarez Enparantza (27 September 1929 – 14 January 2012), better known by his pseudonym Txillardegi, was a Basque linguist, politician, and writer. He was born and raised in the Basque Country, and although he did not learn the Basque language until the age of 17, he later came to be considered one of the most influential figures in Basque nationalism and culture in the second half of the 20th century. He was one of the founders of ETA, but in 1967 he left because he did not agree with its political line. Source: Wikipedia (en)