The Roman Empire is what many think of when we picture Roman civilisation. Overall, Roman culture had three prime periods - the Kingdom, the Republic and the Empire. The Empire was a unified mass in several parts. Based in Italy, the Empire controlled lands from Britain in the north to North Africa in the south. By the late 4th century, the unified empire split into the East and West, with the West falling in 476 AD. The East over time became Hellenised, due to influence from the Empire’s Greek lands. Though due to a mix of sacks by fellow Christian Crusaders and the loss of lands to the Arab Islamic Caliphates, it was conquered by the Ottoman Empire in 1453 AD.
Leaders of the Empire - the Emperors - ruled all organs of the state in the unified Latin empire, during the East and West split, and the Eastern Empire until the Ottoman conquest.
However, what were their titles?
How did they style themselves?
Styles
A style is an official title of a ruler.
As a modern example, King Charles III of the UK is officially styled:
Charles the Third, by the Grace of God of the United Kingdom of Great Britain and Northern Ireland and of His other Realms and Territories, King, Head of the Commonwealth, Defender of the Faith
If we were to break this down, this relates to his name (literally the third sovereign named Charles to rule England, Scotland or Britain), the name of the country he reigns as well as the Commonwealth Realms, being Head of the Commonwealth of Nations, and Defender of the Faith as in Head of the Church of England.
By the Grace of God refers to the concept of ruling by God’s grace or will. It is a reference in part to the divine right of kings, though even before the notion as employed by the early Stuart kings (James VI/I and Charles I), it was still seen that monarchs were on Earth to rule temporally and spiritually.
The same style applied to King Charles’s mother, the late Queen Elizabeth II. Her father, King George VI would have had a style including “Emperor of India”, a title going back to Queen Victoria.
How Roman Emperors were styled followed a similar format.
In the case of Augustus, he was known officially as:
Imperator Caesar Divi Filius Augustus
Imperator originally was used to signify a victorious general. Emperors used it as they commanded the armed forces. Caesar was of course the name of Julius Caesar. He was never an Emperor per se, though the name was later used as an heir to the ruling Emperor. Octavian, as he was known prior to being Augustus, was the heir to Caesar, and thus became known as Gaius Julius Caesar Octavius.
Augustus, the true title denoting being Emperor, was granted to him by the Senate to denote not only leadership of the body but being "venerable”, and thus the leader of the state also.
Divi Filius concerned the religious cult established around Julius Caesar. After his assassination, he was defied by the Senate. Augustus, as Caesar’s adopted son, was essentially calling himself the son of a god, and thus drawing on Caesar’s deified status.
Marcus Aurelius’s full title was - Imperator Caesar Marcus Aurelius Antoninus Augustus.
Imperator meant being the supreme military commander of Rome.
Marcus Aurelius was his name.
Caesar was attained when Emperor Antoninus Pius made him and his adoptive brother Lucius Verus his heirs. Both served as co-emperors following Pius’s death, though Marcus was the senior emperor due to his scholarly nature.
Antoninus was the name he adopted when his predecessor Antoninus Pius made him his legal son.
And Augustus is the label denoting being emperor, and thus venerable above all others in the Empire.
This pattern remained consistent amongst all Emperors and into the Dominate period following Diocletian in the late 3rd century AD.
So, as with current styles, the full scope and nature of the rule of Roman Emperors was so-captured.
For a list of Western Roman Emperors, see here.
For a list of Eastern/Byzantine Emperors, click here.