Gaius Julius Caesar Octavianus (Augustus Caesar, originally born Gaius Octavius Thurinus) was the great-nephew of Julius Caesar, and was later adopted as his son, who lived from 63 BC to 14 AD. Augustus was among the Roman Empire's most powerful leaders, promoting himself to the title of "Princeps," which gradually became the title of Emperor.
Upon viewing the culture on planet 892-IV, Spock noted how the culture was "an amazing example of Hodgkins' Law of Parallel Planet Development, but on this 'Earth', Rome never fell." As a result, the planet became "a world ruled by emperors who can trace their line back 2,000 years to their own Julius and Augustus Caesars. (TOS: "Bread and Circuses")