Perault (or, better, Peyraud), Guillaume, a French prelate, was born about 1190 in Peyraud, a village of Vivarais, then in the diocese of Viennia, now in the department of Ardeche. Doctor of the University of Paris, Guillaume entered quite young the Order of St. Dominic, and soon acquired a general esteem by the purity of his manners, by his doctrines, and by his talents in the pulpit. Philip of Savoy, who, without having received orders, was elected in 1246 archbishop of Lyons, chose him for suffragan bishop, and Guillaume, clothed with a title in partibus, performed episcopal duties in the diocese for more than ten years, which has led into error Leandro Alberti, Altamura, and Severt, who have placed him among the archbishops of Lyons. Perault died at Lyons in 1255. We have of his works, Summa de vitiis et virtu. tibus, of which the last edition (Paris, 1663, 4to) is a work much praised by Gerson: — Commentarium de Re. gula Sancti Benedicti (1500, 8vo); printed without name of place, year, or printer, and attributed in a MS. to William of Poitiers: — a treatise, De eruditione religiosorum; often printed at Paris, Lyons, and elsewhere, and which appeared under the name of Imbert, general of the Dominicans: — a collection of sermons De di. versis et de efstis, of which more than twelve editions have been published; the last at Orleans, 1674, 8vo: — a treatise, De eruditione Principium, printed for the first time at Rome, 1570, 8vo. A treatise entitled Virtutum vitiorumque exempla has been wrongly attributed to Guillaume Perault; it is by Nicholas de Hanappes, patriarch of Jerusalem. See Echard, Scriptor. ordin. Prcedicat. 1:132; Touron, hommes illust. de l'ordre de Saint Dominique; Gallia Christ. vol. 5.