Tim Marcoh was once known as the Crystal Alchemist who was also the lead researcher in the Amestris military's Philosopher Stone project. He is a skilled alchemist and a very intelligent man. His goal is to try and help as many people he can for the rest of his life to repent for the past sins he committed.
In the English dub version of the Fullmetal Alchemist anime series Tim Marcoh was first voiced by Brice Armstrong.
For the English dub of Fullmetal Alchemist: Brotherhood, Brice Armstrong didn't reprise the role since he retired from voice acting. The role was recast and now Tim Marcoh is voiced by Jerry Russell.