Wilhelm Eiselstein

One of ten famous Alchemists and considered a world authority on catalytics – the study of making efficient alchemy - Wilhelm Eiselstein was researching the “Philosopher’s Catalyst,” a legendary material that has powers comparable to the Philosopher’s Stone. When the town of Hiessgart (where he and his daughter resided) came under attack of chimeras, he brought the refugees to safety and led the efforts in building New Hiessgart.

Edward and Alphonse had met the professor and his daughter Selene sometime before events within Fullmetal Alchemist and the Broken Angel, while Ed and Al had been studying with Izumi Curtis. Both brothers recall that Izumi regarded Eiselstein as a friend, and worry that he will tell their teacher about their attempt in Human Transmutation. The professor does guess that they have committed the taboo, but claims to have no interest in their personal lives, and so won't divulge this to Izumi.

He has continued to work on the Philosopher's Catalyst in secret, helping develop chimeras. A number of alchemists, who have run into trouble with the military, head to Hiessgart in the belief that the Professor is trying to create a society run by alchemists and independent of the Amestrian military. Whether Eiselstein actually took part in this, or turned a blind eye to it because of his hopes to create the Catalyst, is never made clear in the story.