Saint Hesychius or Isicius (French: Isice or Hésychius; died c. 490) was a bishop of Vienne in the Dauphiné, France.
According to the historian Bernard Bligny (1979), Hesychius belonged to "one of the principal Gallo-Roman families of 'Bourgogne', the Hesychii, a branch of the Syagrii", of whom several members were bishops of Vienne (three) and Grenoble (four).
[1][3] The Dictionnaire historique de la Suisse states that he was descended from a family of the senatorial nobility and was closely related to the Emperor Avitus.
[7] In his Chronique (VI) Bishop Ado mentions Hesychius as the reigning bishop when Saint Severus of Vienne dedicated a church in Vienne at the time of the death of Saint Germanus of Auxerre.
[5][3] Lucas however maintains that whereas the dedication must have taken place in 448 and Severus' death in 450, Hesychius' episcopacy was later, probably between 475 and 490.