Saint Eustase was a 6th-century prelate who served as the bishop of Bourges. Originally from Autun, he received his religious training at the Abbey of Saint-Symphorien. Before ascending to the episcopacy, he held the positions of deacon and archdeacon within the diocese of Autun. He was elected to lead the see of Bourges following the death of Severe Sulpice in 591, becoming the twentieth individual to hold that specific office.