Constantine Doukas (or Doux) () (died 913) was a prominent Byzantine general. In 904, he stopped the influential eunuch court official Samonas from defecting to the Arabs. In return, Samonas manipulated his father, Andronikos Doukas, into rebelling and fleeing to the Abbasid court in 906/907. Constantine followed his father, but soon escaped and returned to Byzantium, where he was restored by Leo VI the Wise (r. 886–912) to favour and entrusted with high military offices. Upon the death of the Emperor Alexander (r. 912–913), Constantine with the support of several aristocrats unsuccessfully tried to usurp the throne from the young Constantine VII (r. 913–959), but was killed in a clash with supporters of the legitimate emperor.