Hesychius I was a 5th-century bishop of Vienne, located in the Dauphiné region of France. Belonging to a prominent Gallo-Roman senatorial family, he is believed to have served as a senator before his election to the episcopacy. His tenure as bishop is estimated to have occurred between approximately 475 and 490. He was the father of two notable figures, including his successor Avitus, who also served as the bishop of Vienne, and Apollinaris of Valence.