Bernard of Clairvaux
Bernard of Clairvaux (1090-1153, canonized 1174) was an influenced monk of the Cistercian Order. An influential writer, he was also a prolific founder of monasteries - in all, sixty-five were established under his direction.
In the context of Thelema, Bernard is best remembered as having written the original rules of the Knights Templar, which were based on those of the Cisterians. He was also the nephew of one of the original Knights, Andre de Montbard.