Examining the role and position of the Byzantine empress between the fourth and the eighth centuries, this work explores the nature of female imperial power and contrasts it with male power. Was there such a thing as the "office of emperor/empress", or did power depend on individual personalities? This text investigates five questions: who the empress is; how she is titled; how she is talked about; what she looks like; and what she does. The period under discussion takes the reader from the empress-mother Helena, the first overtly Christian empress, to the only "female" emperor in Byzantine history, Eirene, and encompasses the time of the transition from the Roman world to the medieval.