Caesar

Caesar was a title held by the ruler of the Roman Empire. Nero, (TV: The Romans) Julius Caesar, Augustus and Tiberius were known Caesars.

Jesus Christ was executed in the twenty-first year of Tiberius' reign. (PROSE: Byzantium!)

The Tenth Doctor once offered to take Rose Tyler to see an unspecified Caesar (most likely Julius) crossing the Rubicon. (TV: Tooth and Claw)

Alternate timeline
In an alternate timeline, Caesar was a title held by Holy Roman Emperor Winston Churchill. (TV: The Wedding of River Song)