Van Hohenheim

Hohenheim has been alive for centuries. He worked in a lab, which took advantage of "witch trials" as human bait, to create the first Philosopher's Stone. He succeeded, but it cost him his life. Dante, his lover at the moment, attached his soul (much like Al to armor) to the nearest man in the room, reviving Hohenheim. They continued this practice for many years, until Hohenheim fell in love and married Trisha Elric. After he sired Edward and Alphonse, he left for fear that Dante would use them against him, and also because he felt ashamed of his past. Like Dante, his flesh was wearing away, so he wore cologne to mask the scent. He can transmute without circles, because when he died, he saw past the gate, as did Dante.

Hohenheim is a human Philosopher's Stone. Homunculus (Father) was a test subject at a lab in which Hohenheim worked (in fact, Father was the one who named Hohenheim). The king of Xerxes demanded the secret of immortality from the homunculus, and he obliged. A country wide transmutation was formed, and everything had been working as planned. However, at the last minute, Father lies about where the center of the circle is, and engulfs both himself and Hohenheim into the gate. Hohenheim wakes to see everybody in his country dead. He meets Homunculus, who tells him everything and how he has now gained half of the powers of the stone. Homunculus did this out of gratitude, and after these events, Hohenheim travels to Xing and founds the art of Alkahestry.