The rex sacrorum ("king of the sacrifices"), with his wife, the regina sacrorum ("queen of the sacrifices), was the symbolic head of the Roman state religion. The rex was alternatively called rex sacrificulus or rex sacrificus ("sacrificial king").
When the civil and military powers of the king were transferred to two praetors or consuls, upon the establishment of the republican government at Rome, these magistrates were not invested with that part of the royal dignity by virtue of which he had been the high priest of his nation and had conducted several of the sacra publica, but this priestly part of his office was transferred to a priest called rex sacrificulus or rex sacrorum (Liv. II.2; Dionys. IV.74, V.1.) The first rex sacrorum was designated, at the command of the consuls, by the college of pontiffs, and inaugurated by the augurs. He was always elected and inaugurated in the comitia calata under the presidency of the pontiffs (Gell. XV.27), and as long as a rex sacrificulus was appointed at Rome, he was always a patrician, for as he had no influence upon the management of political affairs, the plebeians never coveted this dignity (Liv. VI.41; Cic. pro Dom. 14). But for the same reason the patricians too appear at last to have attributed little importance to the office; whence it sometimes occurs that for one, or even for two successive years no rex sacrorum was appointed, and during the civil wars in the last period of the republic, the office appears to have fallen altogether into disuse. Augustus however seems to have revived it, for we find frequent mention of it during the empire, until it was probably abolished in the time of Theodosius (Orelli, Inscr. n. 2280, 2282, 2283).
Considering that this priest was the religious representative of the kings, he ranked indeed higher than all other priests, and even higher than the pontifex maximus (Festus, s.v. Ordo sacerdotum), but in power and influence he was far inferior to him (Id sacerdotium pontifici subjecere, Liv. II.2). He held his office for life (Dionys. IV.74), was not allowed to hold any civil or military dignity, and was at the same time exempted from all military and civil duties (Dionys. l.c.; Plut. Quaest. Rom. 63;º Liv. XL.42).
His principal functions were:
- 1. To perform those sacra publica which had before been performed by the kings: and his wife, who bore the title of regina sacrorum, had like the queens of former days also to perform certain priestly functions. These sacra publica he or his wife had to perform on all the Kalends, Ides, and the Nundines; he to Jupiter, and she to Juno, in the regia (Varro, de Ling. Lat. VI.12, 13; Macrob. Sat. I.15).
- 2. On the days called regifugium he had to offer a sacrifice in the comitium.
- 3. When extraordinary portents seemed to announce some general calamity, it was his duty to propitiate the anger of the gods. (Festus, s.v. Regiae feriae).
- 4. On the nundines when the people assembled in the city, the rex sacrorum announced (edicebat) to them the succession of the festivals for the month. This part of his functions however must have ceased after the time of Cn. Flavius (Varro, de Ling. Lat. VI.13; Serv. ad Aen. VIII.654). He lived in a domus publica on the via sacra, near the regia and the house of the Vestal virgins (Ambrosch, Studien d. Andeutungen, pp41‑76).
Lacus Curtius - A Dictionary of Greek and Roman Antiquities, by William Smith
- Rex sacrorum in Nova Roma