Theophanu (960 - June 15, 991) also spelled Theophania, was born in Constantinople, and was the wife of Otto II, Holy Roman Emperor.

Otto I, Holy Roman Emperor had requested a Greek princess for his son, Otto, to seal a treaty between the Holy Roman Empire and the Byzantine Empire. Theophanu duly arrived in 972, arriving in grand style with a magnificent escort and bearing great treasure. However, according to the chronicler Thietmar, she was not the virgo desiderata, the Imperial princess, that was expected. Theophanu is identified in the marriage contract as the neptis (niece or granddaughter) of Emperor John I Tzimisces. At one time it was believed Theophanu was the daughter of the Emperor Romanus II and his consort Theophano, but no mention is made of her being porphyrogenita, purple-born, nor are her parents identified. It is unlikely that Theophanu was the daughter of any emperor -- the current theory is that her father was Konstantinos Skleros, brother of the pretender Bardas Skleros and her mother was Sophia Phokaina, niece of Emperor Nicephorus II and the sister of Tzimisces' first wife Maria Skleraina.

Theophanu and Otto were married by Pope John XIII on April 14, 972 at Saint Peter's and she was crowned the same day in Rome. Their children were:
1. Adelaide, Abbess of Quedlinburg, born November or December 977
2. Sophia, Abbess of Gandersheim, born 978
3. Matilda of Saxony, born 978
4. Otto III, Holy Roman Emperor, born June or July 980
5. A daughter, a twin to Otto, who died before October 8, 980

Theophanu accompanied her husband on all his journeys, and issued diplomas in her own name as Empress. It is known she was frequently at odds with her mother-in-law, Adelaide of Italy, and this caused an estrangement between Otto II and Adelaide. According to Odilo, Abbot of Cluny, Adelaide was very happy when "that Greek woman" died. Albert of Metz describes Theophanu as being an unpleasant and talkative woman. Theophanu was also criticized for introducing luxurious garments and jewelry into Germany. She is credited with introducing the fork to Western Europe - chronographers mention the astonishment she caused when she "used a golden double prong to bring food to her mouth" instead of using her hands as was the norm. "The theologian Peter Damian even asserts that Theophanu had a love affair with John Philagathos, a Greek monk who briefly reigned as Antipope John XVI.

Otto II died suddenly on December 7, 983 and was buried in Rome. That Christmas Theophanu had their three-year-old son crowned as Otto III, with herself ruling as Empress Regent on his behalf. Henry II, Duke of Bavaria seized Otto in spring 984, but was forced to surrender the child to his mother. With the cooperation of Willigis, Archbishop of Mainz, and Hildebald, Bishop of Worms, Theophanu reigned until her death in 991. She was buried in the church of Saint Pantaleon at Cologne. The chronicler Thietmar eulogized her as follows: "Though [Theophanu] was of the weak sex she possessed moderation, trustworthiness, and -- which is not often found in Greece -- good manners. In this way she protected with male vigilance the royal power for her son, friendly with all those who were honest, but with terrifying superiority against rebels."

Because Otto III was still a child, his grandmother Adelaide of Italy took over the regency until Otto III became old enough to rule on his own.