Bernard Ayglerius (also spelled Aiglerius, Aygler, Ayglier, or Aiglier) (1216 – 4 April 1282) was a French theologian, papal legate, and cardinal.
He caught the eye of Pope Innocent IV and was made a papal chaplain sometime before 1244, when he appeared as the auditor of the Sacra Rota Romana.
At Montecassino he recalled the monks from exile, commissioned an inquiry into the monastery's ancient rights (1270s), reformed monastic discipline, recovered lost property, founded a hospital at San Germano, convened a synod, and granted a church to the Dominicans at the request of Thomas Aquinas.
He frequently acted as a papal legate: in France against the Cathars and in Constantinople against the Greek Orthodox and in promoting a Crusade.
Upon his return from Constantinople he found Angevin troops occupying the castle of Montecassino and convinced Charles of Anjou to remove them.