Benedictus Ducis (* about 1492 in Constance; † end of 1544 near Ulm) was a German composer and Protestant pastor. Initially active as an organist in Antwerp and London (1515). He also appeared as a Protestant pastor in Geislingen an der Steige and in the hospital in Ulm. After a stopover in Stubersheim (near Ulm) he served in the parish of Schalkstetten until his death in 1544. He was said to have a violent temper and a tendency to drink.

In addition to powerful Catholic church music, Ducis also composed simple chorales in the spirit of Lutheran thought. His vocal works include "An Wasserflüssen Babylon" and "Nun freut euch, lieb Christen gmein".