Sex offered intimate access to the emperor; imperial sex partners therefore were potentially amongst the most influential members of court, even if they lacked official positions or were of low social status. This chapter begins by discussing and explaining an historical anomaly: the absence at Rome of a ‘harem’ – an institutionalized reserve of women attached to the court as exclusive sexual partners for the emperor. It then examines the access to the emperor that sexual partners like concubines had, and the influence of these partners on court dynamics. Finally, it considers the role of sex, sexuality, and gender expression in the performance of imperial power at court. Underlying the analysis are the often outrageous tales told by the sources about emperors’ sex lives; the chapter argues that these cannot be simply taken at face value but are useful in reconstructing patterns of thinking about how sex intersected with imperial power.