Phoenix Nero is a Bronze Knight in the animated series Knights of the Zodiac, a retelling of the classic Saint Seiya story. He is the Knight of the constellation Phoenix and the elder brother of Andromeda Shaun, another Bronze Knight, making their sibling bond a central part of his identity. Nero trained on Death Queen Island to earn the Phoenix armor, but his past was shaped by hardship. He was originally an honorable and caring child, fierce and tough in nature but deeply protective of his younger sister, whom he taught to defend herself. However, years of cruel and inhumane training on Death Queen Island, along with a devastating loss suffered there, changed him completely. He buried his former self in flames along with all his pain and sorrow, and came to define himself by his wrath, his hatred, and his pride as the Phoenix Knight.

Physically, Nero is a muscular and imposing young man with tan skin, navy blue hair, and silvery blue eyes. His presence is striking, and when he fights he appears bathed in burning Cosmo, the inner energy that powers the Knights. As a warrior, his abilities are fitting for the Phoenix constellation, being closely attuned to fire. He is able to manipulate Cosmo to generate raw energy for a wide range of superhuman feats, and his signature technique is Phoenix Rising.

In the story, Nero begins as a rogue Phoenix Knight serving under Vander Guraad, an antagonist who seeks to destroy Sienna, the reincarnation of the goddess Athena. Driven by bitterness and a desire for power born from his suffering, he stands in opposition to the other Bronze Knights, including his sister. His motivations during this period are rooted in the anger and resentment that consumed him after his traumatic past. Over time, however, he turns against Guraad and ultimately rejoins the side of Athena, allowing his role to shift from adversary to ally. This change is part of his larger development, as he moves from a vengeful outcast to a Knight who confronts his own darkness and reclaims a sense of purpose. A key moment in his arc occurs during the battle for Sanctuary, when he faces the immensely powerful Gold Knight Virgo Shaka. To have any chance of overcoming Shaka's overwhelming strength, Nero must dig deep into his soul and accept the possibility of his own death, an experience that reflects the phoenix theme of destruction and rebirth. Through these trials, he gradually reconnects with the person he once was, while still carrying the fury and pride that became his defining traits.