The Roman empresses were the consorts of the Roman emperors, the rulers of the Roman Empire. The duties, power and influence of empresses varied over time depending on the time period, contemporary politics and the personalities of their husband and themselves. Empresses were typically highly regarded and respected, and many wielded great influence over imperial affairs. Several empresses at times served as regents on behalf of their husbands or sons and a handful ruled as empresses regnant, governing the empire in their own right without a husband.

There was no single official term for the position of empress in Ancient Rome. Typical Latin titles included augusta (Greek: αὐγούστα, augoústa), the female form of the male imperial title augustus, and caesaraea (Greek: καισᾰ́ρειᾰ, kaisáreia), the female form of the male imperial title caesar. In Greek, empresses could be referred to as βᾰσῐ́λῐσσᾰ (basílissa), the female form of the male title basileus (denoting a monarch) and αὐτοκράτειρα (autokráteira), the Greek version of the Latin autocratix, the female form of the male title autokrator (denoting a sole ruler). In the third century, empresses could also receive various honorific titles, such as māter castrōrum "mother of the castra" and māter patriae "mother of the fatherland". Titles such as augusta were not used by all empresses, and since such titles could also be granted to other imperial women, such as mothers, sisters and mistresses of emperors, not all women who bore the title were empresses either.

Given that there were sometimes more than one concurrent Roman emperor, there were also sometimes two or more concurrent Roman empresses. For most of the period from 286 to 480, the Roman Empire, though remaining a single polity, was administratively divided into the Western Roman Empire and the Eastern Roman Empire. Through most of this period, the separated imperial courts had their own lines of succession, and as a result their own sequences of concurrent Roman empresses. The western empire fell in the late 5th century, its final empress being the wife of Emperor Julius Nepos. The eastern empire, often referred to as the 'Byzantine Empire' by modern historians, endured for almost another millennium until its fall through the fall of Constantinople in 1453. The final empress of the east, and final Roman empress overall, was Maria of Trebizond, wife of Emperor John VIII Palaiologos. In addition to basílissa and autokráteira, many later eastern empresses bore the title δέσποινα (déspoina), the female form of the male title despotes, a common title in the later empire.

Though the constitutional power of empresses was never defined, it was generally accepted that their coronation, performed after that of their husbands, granted them some imperial power. Often, their primary duties were to oversee the organization of ceremonies at the imperial court as well as to partake in imperial and religious affairs. Although governmental power was most often vested only in the emperor, empresses could gain significant authority as regents for young children or when their husbands were absent. Though they were bound by the wishes and temperaments of their husbands, empress consorts could at times also effectively become influential co-regents. In some cases, emperors reinforced their legitimacy through marrying the daughter of a previous emperor. In such cases, empresses sometimes stressed their dynastic legitimacy, greater than that of their husbands, to achieve great influence. Several influential consorts, such as Theodora, wife of Justinian I, and Euphrosyne, wife of Alexios III, held their own courts. Empresses who ruled in their own right, such as Irene and Zoë Porphyrogenita, sometimes adopted male titles such as basileus and autokrator to illustrate their power.^[1]

During the later 'Byzantine' period, virtually all empresses (unless noted) received the title augusta; whether it was still considered a formal title or just a courtesy title synonym to "empress" is not known.

• List of Roman emperors
• List of Byzantine emperors
• List of Augustae
• List of Latin Empresses of Constantinople
• List of empresses of the Byzantine successor states
• List of Greek royal consorts