Wilhelm Eiselstein

Eiselstein carries himself as a private, principled figure who keeps other people's confidences. When he correctly works out that Edward and Alphonse have broken the human transmutation taboo, he declines to carry the news to their teacher, Izumi Curtis, insisting that their personal affairs are no business of his. His protective streak surfaces during the chimera assault on Hiessgart, where he steers survivors clear of the danger and leads the founding of New Hiessgart. Whether his quiet ambition ever crossed ethical lines is left deliberately unresolved.

The professor makes his home in Hiessgart alongside his daughter and devotes himself to the Philosopher's Catalyst, a fabled substance said to rival the Philosopher's Stone in power. He had crossed paths with the Elric brothers once before the game's events, back when the boys were studying under Izumi, who counted him a friend. Returning to the ruined town, Edward and Alphonse find the grave of his daughter Selene and meet a red-haired girl, Armony, whom Wilhelm presents as his own daughter, the truth of her tie to him forming one of the story's central riddles. Behind the scenes he keeps pushing the Catalyst research forward and lends a hand in producing chimeras. Alchemists at odds with the military drift toward Hiessgart, convinced the professor means to build a nation governed by alchemists and independent of Amestrian control, though the narrative never confirms how far he was truly involved.

His fame rests on catalytics, the discipline aimed at making alchemy more efficient, a field in which he is treated as a global authority. That expertise fuels both his search for the Philosopher's Catalyst and his part in chimera development. Notably he never enlists as a State Alchemist, which may explain why the other nine famed alchemists go unnamed; the honor seems reserved for practitioners of his rank who decline military service, a group that could well include Izumi Curtis herself. His character design draws on the real-world physicist Albert Einstein, echoed in both his German first name and his surname.