In the Middle Ages, men ruled -- except when women did. Here are a few of the medieval women who wielded power in the Byzantine empire, whether through unconventional activities, or the conventional women's role in dynastic connections.
Daughter of Theophano and the Byzantine Emperor Romanus II, and thus sister of the Theophano who married western Emperor Otto II, Anna was married to Vladimir I of Kiev -- and her marriage was the occasion of his conversion, beginning the official conversion of Russia to Christianity.
Anna Comnena, a daughter of a Byzantine emperor, was the first woman to write a history. She was also involved in history, attempting to substitute her husband for her brother in the succession.
Married to Emperor Leo IV, after his death she became regent and co-ruler with her son, Constantine VI. He was unpopular and she was able to depose him, ordering him blinded, then ruling in her own right until she was finally deposed by palace officials. She took an active role in the controversy over icon veneration. The occasion of her rule was used by the Pope to crown Charlemagne as the Emperor of the Romans.
Irene Angelina(1181-1208; Byzantium)
Daughter of Emperor Isaac II Angelos, she married Roger III of Sicily. The year after he died, she was taken by the Germans and married to Philip of Swabia. She later helped persuade Philip to divert the Fourth Crusade to Constantinopole to assist her father and brother. She had four daughters, who each married powerful men: Beatrice married Otto IV, the Holy Roman Emperor; Cunigunde married King Wenceslaus I of Bohemia; Maria married Henry II, Duke of Brabant; Elisabeth married King Ferdinand III of Castile. Through her daughters, she was ancestor of many of the kings and queens of Europe.
Irene Lascarina(? - 1239; Byzantium, Nicaea)
Irene (or Eirene) Lascaria (Laskaris) was the daughter of Theodore I Laskaris of Nicaea; her mother was Anna Angelis, daughter of Emperor Alexios III and Euphrosyne Doukaina Kamaterina. When her first marriage to Andronikos Palaiologos ended with his death, her father married her to the successor he had chosen, John III Doukas Vatatzes. She was badly injured giving birth to their son, Theodore II Doukas Laskarias, and spent the rest of her life in a convent.
Wife of two Byzantine emperors, she served as regent for her sons and married her daughters to important 10th century rulers - the Western emperor Otto II and Vladimir I of Russia.