Julio Chesaré is a character from The Familiar of Zero series. He is a seventeen-year-old priest and knight hailing from the Holy Empire of Romalia. His most distinctive feature is his heterochromatic eyes, one red and one blue, which are referred to as Moon Eyes because they mirror the two moons of the world of Halkeginia. With his handsome, almost neutral beauty, he immediately stands out upon his arrival as a transfer student at the Tristain Academy of Magic.

On the surface, Julio appears calm, worldly, and effortlessly charming. Unlike the vain and foolish Guiche, whom he superficially resembles, Julio carries himself with a sophisticated and composed demeanor that quickly makes him popular among the female students. However, this pleasant exterior conceals a more calculating nature. In the novels, he is portrayed as rather manipulative, a trait that aligns with his role as a key operative for the powerful Pope Vittorio of Romalia.

Julio's motivations are deeply tied to his devotion to the Pope and the overarching religious goals of Romalia. He is not a mage, meaning he cannot use conventional magic, but he is a highly skilled dragon knight and an expert swordsman. His personal dragon is named Azzurro. He is sent to Tristain to support Princess Henrietta's expedition to the troubled nation of Albion, but his true purpose is more secretive.

His role in the story is initially that of a rival to the protagonist, Saito. He arrives at the academy when most of its male students have left for war, and he quickly proves himself Saito's equal. To the irritation of Saito, Julio shows an interest in Louise, and he challenges Saito to a duel, with the prize being a kiss from her. During this duel, Julio, who could have easily won, deliberately loses to tease his opponent. Despite this rivalry, he later helps mend the relationship between Saito and Louise on several occasions.

Key to understanding Julio is his true identity. It is confirmed that he is Vindalfr, also known as the Right Hand of God. He is a familiar, bound to the void mage Pope Vittorio. His runic name grants him the extraordinary ability to control any magical creature. This power makes him a formidable force, as demonstrated when he single-handedly takes on and defeats nine dragon knights of Albion. In the light novels, his role expands further; after the death of the Gallian king Joseph, he becomes the familiar of the new ruler, Josette, gaining the additional power of Mjodvitnir, the Mind of God.

His background reveals he was an orphan, named "Julio Chesare" by his fellow orphans in reference to the great emperor Julius Caesar. This history as an outsider, combined with his role as a servant to the Pope, shapes his development. He is treated with some disdain by others who are wary of his status as a priest, yet he remains a calm and essential agent of the Pope's grand plan to launch a crusade to reclaim the Holy Land from the elves. Throughout the series, his skills are consistently portrayed as being on par with, or even surpassing, Saito's abilities when Saito does not use his own Gandalfr runes.