Conan IV of Penthièvre (1138 – February 20, 1171), (Breton: Konan V Penteur, and Konan Breizh) called "the Young", is duke of Brittany, from 1156 to his death.

He is son of Alan the Black, 1st Earl of Richmond and Bertha of Brittany.

He is his mother's heir; she is the daughter of Duke Conan III.

From his father’s side, Conan is great great grandson of duke Geoffrey I and great grandson of Odo of Brittany.

Conan and his daughter Constance will be the only representatives of the Penthièvre dynasty of Brittany.