Agostino Valier (7 April 1531 – 24 May 1606), also Augustinus Valerius or Valerio, was an Italian cardinal and bishop of Verona.

He was a reforming bishop, putting into effect the decisions of the Council of Trent by means of administrative and disciplinary measures.

[5] Agostino was the nephew of Cardinal Bernardo Navagero (1507 – 1565), and assumed his position as bishop when his uncle died.

Valier as bishop from 1565 was influenced by his reforming predecessor at Verona, Gian Matteo Giberti, as well as the Council of Trent, and his association with Carlo Borromeo.

[6] He followed Borromeo's Milan model but not slavishly, working within local tradition, while also handling the Venetian dominance in a diplomatic fashion.