Leopold III was a 12th-century ruler of the House of Babenberg who served as the Margrave of Austria from 1095 until his death in 1136. Born in Melk, he significantly increased the influence of his dynasty through his second marriage to Agnes, the sister of Emperor Henry V. Known as Leopold the Good, he was a key figure in the development of the region, fostering urban growth and establishing several important religious institutions. He was canonized in 1485 and is recognized as a patron of Austria and Vienna.