Theophanu was a Byzantine princess and later Holy Roman Empress during the late 10th century. In 972 she married Otto II, a prince from the ruling Ottonian dynasty of the Holy Roman Empire. Her marriage arrangement caused some controversy, because she was only the niece, and not the daughter of the Eastern Roman Emperor. Nevertheless after several negotiations the two were wed, and a year later they ascended the throne after the death of Otto I. Theophanu is assumed to have had both prestige and influence in court because of her frequent mention in official documents. After the death of her husband in 983, she ruled as regent during which she quarreled often with her mother-in-law Adelaide of Italy. As regent she negotiated peace, welcomed diplomats and secured the futures of her children including Otto III who later became emperor. She died of illness in 991, still a young woman, but her political accomplishments and ambitions had an important influence on history, for which her reputation and legacy is still remembered and admired over a millennium later.