The gens Julia or Iulia was one of the most ancient patrician families at Ancient Rome. Members of the gens attained the highest dignities of the state in the earliest times of the Republic. The first of the family to obtain the consulship was Gaius Julius Iulus in 489 BC. The gens is perhaps best known, however, for Gaius Julius Caesar, the dictator, and grand uncle of the emperor Augustus, through whom the name was passed to the so-called Julio-Claudian dynasty of the 1st century AD. The nomen Julius became very common in imperial times, as the descendants of persons enrolled as citizens under the early emperors began to make their mark in history.
The Julii were of Alban origin, mentioned as one of the leading Alban houses, which Tullus Hostilius removed to Rome upon the destruction of Alba Longa. The Julii also existed at an early period at Bovillae, evidenced by a very ancient inscription on an altar in the theatre of that town, which speaks of their offering sacrifices according to the lege Albana, or Alban rites. Their connection with Bovillae is also implied by the sacrarium, or chapel, which the emperor Tiberius dedicated to the gens Julia in the town, and in which he placed the statue of Augustus. Some of the Julii may have settled at Bovillae after the fall of Alba Longa.
As it became the fashion in the later times of the Republic to claim a divine origin for the most distinguished of the Roman gentes, it was contended that Iulus, the mythical ancestor of the race, was the same as Ascanius, the son of Aeneas, and founder of Alba Longa. Aeneas was, in turn, the son of Venus and Anchises. In order to prove the identity of Ascanius and Iulus, recourse was had to etymology, some specimens of which the reader curious in such matters will find in Servius. Other traditions held that Iulus was the son of Aeneas by his Trojan wife, Creusa, while Ascanius was the son of Aeneas and Lavinia, daughter of Latinus.