Constantine Doukas or Ducas was Byzantine junior emperor from 1074 to 1078, and again from 1081 to 1087. He was born to Emperor Michael VII Doukas and Empress Maria of Alania in about 1074, and elevated to junior emperor probably in the same year. He was junior emperor until 1078, when Michael VII was replaced by Nikephoros III Botaneiates. Because Constantine was not made junior emperor under Nikephoros III, his betrothal to Olympias, the daughter of Robert Guiscard, was broken, which Robert Guiscard used as a pretext to invade the Byzantine Empire. John Doukas forced Nikephoros to abdicate in favor of Alexios I Komnenos in 1081, and shortly afterwards Alexios elevated Constantine to junior emperor. Constantine married Alexios's daughter Anna Komnene, and remained junior emperor until 1087, when Alexios had a son, John II Komnenos. Constantine died in c. 1095.

Michael VII Doukas or Ducas, nicknamed Parapinakes, was the senior Byzantine emperor from 1071 to 1078. He was known as incompetent as an emperor and reliant on court officials, especially of his finance minister Nikephoritzes, who increased taxation and luxury spending while not properly financing their army. Under his reign, Bari was lost and his empire faced open revolt in the Balkans. Along with the advancing Seljuk Turks in the eastern front, Michael also had to contend with his mercenaries openly turning against the empire. Michael stepped down as emperor in 1078 and later retired to a monastery.