Theodora Porphyrogenita became the sole ruler of the Byzantine Empire after the death of her brother-in-law Constantine IX Monomachos. Theodora Porphyrogenita: Theodora Porphyrogenita was the reigning Byzantine Empress from 21 April 1042 to her death on 31 August 1056, and sole ruler from 11 January 1055. She was the last sovereign of the Macedonian dynasty, which had ruled the Byzantine Empire for almost 200 years. January 11, 1055. Wiki link