A young sailor who has grown up in touch with nature and has always been an outcast, deemed uncanny, a sorcerer, or suspicious by the people of Saint-Sampson. By teaching himself trades such as carpentry, blacksmithing, and navigation, he has established an independent and isolated life. Due to his secret and epic love for Déruchette, he assumes a task equivalent to suicide: retrieving the engine of the broken La Durande. For two months, he faces hunger, storms, cold, and a giant octopus on the Douvre rocks, achieving the impossible. When he returns and sees that the girl who is his prize appears happy with someone else (Ebenezer), he chooses the silent withdrawal typical of great heroics. He sends the young couple away and ends his epic life in tragedy by allowing the waters to swallow him in a hollow by the ocean.
He is the child of a woman who immigrated to Guernsey after the French Revolution, with her origin unknown. She settled in a ruin called Bû de la Rue, and after she died, Gilliatt grew up alone in that house. The townspeople thought his mother was a witch and always treated him with suspicion and hostility. This social isolation deepened his inner world and turned him into a man with a sharp wit, resilient and mysterious, oriented toward nature.
Though in his thirties, the gloom of the sun and sea makes him look forty-five; he is a man with strong, massive features resembling those of the Dacian barbarians in ancient carvings, wearing a harsh, deep, wavy, and iridescent mask on his face, except for a childlike smile and teeth as white as ivory. He usually wears coarse brown sailor shirts and leather clothing.
Déruchette
He loves her with a semi-divine silence and passion. She is a source of inspiration for Gilliatt. However, he renounces her for the sake of her happiness.
Sieur Clubin
Gilliatt finds the proof of his dishonesty and death by chance at the bottom of the sea in the arms of an octopus and recovers the fortune from him.
Ebenezer Caudray
Because of his love for her, he looks at him not with jealousy, but as the man who will make the girl he loves happy, and he helps them with his own hands.
Üstat Lethierry
He respects him and volunteers to salvage the machine to alleviate Lethierry's despair.