Theophanu (955–991) was a Byzantine princess who became Holy Roman Empress through marriage to Emperor Otto II. As the trusted political partner of her husband and later the regent of her young son Otto III, she left a remarkable legacy as one of the most powerful female rulers of the Ottonian era as well as of the Holy Roman Empire's history in general. Her reign is associated with the exchange of political, religious and cultural ideas and international activities between the Western Empire and the East, including the Byzantine Empire as well as the Slavic countries. Although the empress's personal role in some aspects of these processes is a subject of debate, she is often depicted in historiography and artistic portrayals as a cultured, spirited woman who had to adapt to a difficult situation after her husband's death and whose political vision was unfulfilled due to the early deaths of herself and her son. This image is also influenced by the masculine posture she adopted in her lifetime as coimperatrix and even imperator.

The Marriage Charter of Empress Theophanu is the dower document for the Byzantine princess Theophanu. Written in Latin, the document was created after the marriage of Theophanu to Emperor Otto II in 972, which made her the empress of the Holy Roman Empire. The document was prepared by Otto II and exemplifies an instance of political and cultural contact between the Holy Roman Empire and the Byzantine Empire.