There is no single fixed answer, because “Caesar” started as one man’s family name and then turned into a title used by many rulers over centuries.

The short answer

  • If you mean Julius Caesar himself: 1 person.
  • If you mean the famous early Roman rulers often called “the Twelve Caesars” (from Suetonius’ book): 12 men, from Julius Caesar to Domitian.
  • If you mean everyone who used “Caesar” as part of the imperial title in the Roman Empire, there were roughly 70+ emperors in the West alone, and more if you include Eastern emperors and co-emperors.

What “Caesar” originally meant

  • “Caesar” was originally the family name of Gaius Julius Caesar, the Roman general and dictator killed in 44 BCE.
  • His adoptive son Octavian (Augustus) turned “Caesar” into part of the imperial name, so later emperors used it to signal succession and legitimacy.

The famous “Twelve Caesars”

When people online or in quizzes ask “how many Caesars were there?”, they often mean the group from Suetonius’ work De vita Caesarum (“The Life of the Caesars”), now commonly called The Twelve Caesars.

Those twelve are:

  1. Julius Caesar
  2. Augustus
  3. Tiberius
  4. Caligula
  5. Claudius
  6. Nero
  7. Galba
  8. Otho
  9. Vitellius
  10. Vespasian
  11. Titus
  12. Domitian

These cover the Julio-Claudian and Flavian dynasties, plus the chaotic “Year of the Four Emperors” (Galba, Otho, Vitellius, Vespasian) in 69 CE.

How it turned into a title

  • Over time, “Caesar” became a rank: often the designated junior emperor or heir, paired with a senior “Augustus”.
  • During the Tetrarchy and later, there could be multiple “Caesars” at once (for example, one in the West and one in the East), which makes counting them tricky.

Total number across Roman history

Historians usually talk in ranges because of civil wars, usurpers, and overlapping claims.

  • About 70 emperors are commonly counted for the Western Roman Empire from Augustus to the fall in 476 CE.
  • If you include Eastern Roman/Byzantine rulers and all those who held the junior rank of “Caesar,” the number of individuals using “Caesar” as a name or title rises well above 70, possibly into the hundreds, depending on where you draw the line.

In forum and trivia discussions today, most people either mean the “Twelve Caesars” from Suetonius or they’re using “Caesars” loosely to refer to all Roman emperors, which is why you see different numbers quoted.

TL;DR:

  • One Julius Caesar.
  • Twelve “Caesars” in the classic Suetonius set.
  • Roughly 70+ emperors in the West, and well over that if you count every ruler or co-ruler who used “Caesar” as a title.

Information gathered from public forums or data available on the internet and portrayed here.