The Julii Caesares were the most illustrious family of the patrician gens Julia. The family first appears in history during the Second Punic War, when Sextus Julius Caesar was praetor in Sicily. His son, Sextus Julius Caesar, obtained the consulship in 157 BC; but the most famous descendant of this is Gaius Julius Caesar, a general who conquered Gaul and became the undisputed master of Rome following the Civil War. Having been granted dictatorial power by the Roman Senate and instituting a number of political and social reforms, he was assassinated in 44 BC. After overcoming several rivals, Caesar's adopted son and heir, Gaius Julius Caesar Octavianus, was proclaimed Augustus by the senate, inaugurating what became the Julio-Claudian line of Roman emperors.
The first of the Julii Caesares to appear in history was Sextus Julius Caesar, praetor in Sicily in 208 BC. From the filiation of his son, Sextus, "Sex. f. L. n.", we know that his father was named Lucius, but precisely who this Lucius was and whether he bore the surname Caesar is uncertain. On the assumption that the Caesares were descended from earlier notable families of the Julia gens, some scholars have suggested that he was the son of Lucius Julius Libo, consul in 267 BC.
The Dictionary of Greek and Roman Biography and Mythology says this of the cognomen Caesar: