Christian-Joseph Guyonvarc'h (18 October 1926, Auray – 9 January 2012, Guilers) was a French philologist and linguist who specialised in Celtic studies.

Christian-Joseph Guyonvarc'h was born on 18 October 1926 in Auray, Brittany (France), and grew up in a French-Breton bilingual environment.

Georges Dumézil directed Le Roux's first studies and was president of the jury at Guyonvarc'h's doctorate thesis in 1980.

[1][2] Guyonvarc'h taught Old Irish and Breton at Rennes 2 University.

[1][2] From 1979 to 1981, he was a member the patronage committee of Nouvelle École, the annual magazine of the ethno-nationalist think tank, GRECE.