Scar's Brother
Scar’s Brother giving up his life and arm to save Scar’s after he had been gravely wounded.
Just like Scar his real name has never been revealed.
In the 2003 anime, he created Lust during a failed human transmutation, while attempting to bring back his lover.
In the 2009 anime, his research was what lead to a transmutation circle that was used against Homunculus; it was used to negate Homunculus’ control of alchemists’ abilities.