Olivier, Cardinal a German theologian and historian, was born in Westphalia about the middle of the 12th century. After studying at Paderborn he became canon of the church of that city, and afterwards director of the schools of Cologne. In 1210 he went to the south of France to preach a crusade against the Albigenses. After returning to his native country he preached a crusade against the Saracens in Westphalia, Friesland, Flanders, and Brabant, and in 1214 and 1217 went himself to the Holy Land with the volunteers. In 1222, having returned to Europe, he was made bishop of Paderborn; and while at Rome, in 1225, he was created cardinal-bishop of Sabina, and entrusted by the pope with a mission to the emperor Frederick. He died soon after at Sabina, in 1227. He wrote a letter to Engelbert, archbishop of Cologne, repeatedly published, as in Bongars, Gesta Dei per Francos; Bistoria rieguni Terroce Sinctae, in, Eckard, Coypus historics, 2:1355; Historiac Damiatina, in the same, 2:1398. Michaud has given an analysis of these works in his Bibliotheque des Croisades, p. 177; and Petit Radel umentions the most important passages in the Hist. Litter. de la France. See Schatenius, Annales Paderbornenses; Historiens de France, vol. 18; Ughelli, Italia Sacra, 1:167; Hist. Litter. de la France, 18:14.