Duke Duffau is a supporting character from the anime Chrono Crusade, known primarily for his role as a powerful demon and a key figure in the conflict against the primary antagonist, Aion. His name reflects his noble rank, as he is a duke within the hierarchy of Pandemonium, the demonic realm from which he hails. He is also identified as the leader of a faction known as the Pursuers, a group of demons who have declared war on Aion and his followers, the Sinners.

In terms of appearance, Duffau is characterized as an adult male demon with distinct physical traits. He has black hair cut to ear-length and piercing red eyes. His demonic nature is most prominently displayed by his large horns, which are described as being shaped similarly to scythes, a feature that visually underscores his combative prowess. His attire often includes a coat, scarf, and a cowboy hat, giving him a distinctive and somewhat anachronistic style among the series' cast.

Duke Duffau's personality is heavily shaped by loss and a singular, driven focus. He is presented as a cold and fierce warrior, a disposition that emerged following the death of Margret, who is identified as his eternal soul mate. Her passing left him hardened, turning him into a vicious combatant with little patience for sentimentality. Despite this hardened exterior, his actions are motivated by a clear purpose: he seeks to eliminate Aion and restore darkness to Pandemonium, viewing the Sinners as a threat to the demon world's natural order.

Within the narrative, Duffau serves as a temporary and uneasy ally to the protagonists. Recognizing a common enemy in Aion, he seeks an allegiance with the Order of Magdalene, specifically approaching Rosette Christopher and her partner, the demon Chrono. His proposition forces the Order to debate the wisdom of allying with a powerful demon, ultimately leaving the decision to Rosette. In this role, he provides crucial exposition, revealing to Rosette that she is the reincarnation of Mary Magdalene and possesses the power of an Apostle, a revelation accompanied by the appearance of stigmata-like marks on her body. His knowledge of these ancient spiritual matters highlights his age and experience within the supernatural world.

His key relationships are adversarial. He is fundamentally opposed to Aion, and his primary goal is to amass enough power to defeat him and his Sinner faction. He leads his own army in this effort and is credited with having successfully eliminated one of the Sinners, a demon named Genai. While he allies with Chrono and Rosette, this relationship is one of convenience born from a shared goal, not of trust or friendship.

Duke Duffau does not undergo significant personal development during his appearance, as his role is more functional than transformative. He is a static character whose established motivations drive the plot forward at a critical juncture. His fate, however, differs between versions of the story. In the anime continuity, he is ultimately slain by the power of Rosette’s holy blood. In the source material, he perishes while leading his troops in a direct attack on Aion. Regardless of the version, his demise is a foregone conclusion, serving to demonstrate the immense power of his enemies and the high stakes of the central conflict.

In terms of notable abilities, Duke Duffau is a high-ranking demon whose power is considerable, evidenced by his noble title within Pandemonium's hierarchy, though he is acknowledged to be less powerful than both Aion and Chrono. His scythe-shaped horns signify that his strength is specialized for combat and offense, sacrificing higher defensive capabilities that other demons might possess. He is also a capable military leader, commanding his own army of Pursuers and strategizing to eliminate powerful targets like Genai.