Henry Suso (also called Amandus, a name adopted in his writings, and Heinrich Seuse in German) was a German mystic, born at Überlingen on Lake Constance on 21 March c. 1300; he died at Ulm on 25 January 1366; declared Blessed in 1831 by Gregory XVI, who assigned his feast in the Dominican Order to 2 March. The Dominicans now celebrate his feast on 23 January, the feria, or "free" day, nearest the day of his death.

Suso and his friend Johannes Tauler were students of Meister Eckhart. The three form the nucleus of the Rhineland school of mysticism. As a lyric poet and troubadour of divine wisdom, Suso explored with psychological intensity the spiritual truths of Eckhart’s mystical philosophy. His devotional works were extremely popular in the later Middle Ages.

He assumed the name of his mother, his father being a Herr von Berg. In Das Büchlein der ewigen Weisheit (The Little Book of Eternal Wisdom), written between 1327 and 1334 in Constance, he discusses the practical aspects of mysticism. The latter work, which Suso also translated into Latin under the title of Horologium sapientiae (Clock of Wisdom), has been called the finest fruit of German mysticism.