In chapter 58 of the Fullmetal Alchemistmanga, this man is introduced as Roy Mustang's teacher and Riza Hawkeye's father. He dies soon after he is introduced, coughing blood in a similar way to Izumi Curtis, the Elric brother's teacher. He seems to be annoyed that Roy had joined the military. It has been theorized that he was the one who gave Riza the tattoo showing Roy's sigil (his alchemic circle) since Hawkeye-sensei taught Roy his alchemy.
Hawkeye-sensei looks like a Hughes/Ed/Shou Tucker chimera.