The name Julien is derived from the Roman family name Iulius or Julius, which traces its origins to the ancient Roman gens (clan) Iulia. The gens Iulia was a patrician family that rose to prominence during the Roman Republic, and one of the most renowned members was Gaius Julius Caesar.

The name Julius likely comes from the word "Iovilios," meaning "descendant of Iove" or Jupiter, the chief deity in Roman mythology. It has been suggested that the name may also be related to the Greek word "ioulos," meaning "downy-bearded," referring to the youthful appearance of the first bearer.

One of the earliest recorded instances of the name Julien can be found in the 4th century CE, when it was borne by Saint Julien de Brioude, a Christian martyr from Gaul (modern-day France). The name gained popularity in France during the Middle Ages, and several French kings bore the name, including Julien de Rieux (1238-1286) and Julien de Clermont-Tonnerre (1370-1416).

In the 12th century, Julien Garnier (c. 1120-1185) was a French Benedictine monk and writer who authored a Latin chronicle of the First Crusade. Another notable figure was Julien de Vézelay (c. 1075-1141), a French Benedictine monk and preacher who played a significant role in promoting the Second Crusade.

During the Renaissance, Julien de' Medici (1453-1519) was an Italian nobleman and co-ruler of Florence, known for his patronage of the arts and his role in the Pazzi conspiracy against his brother Lorenzo. In the realm of literature, Julien Pevelair (1674-1744) was a French playwright and satirist whose works criticized the excesses of the aristocracy.

In more recent times, Julien Offray de La Mettrie (1709-1751) was a French physician and philosopher who advocated a materialist view of the human mind, while Julien Sorel (1806-1880) was a French admiral and politician who served as the Prime Minister of France in 1877.