Klemin

Brigadier General Klemin was a member of the Amestrian Military Command and as such, is in on Father's plan for The Promised Day and has secretly sold out his country for the sake of his own immortality.

His Part in the Story
Klemin is in charge of locating and arresting Izumi Curtis for use as a Human Sacrifice and also commands the ground troops when Roy Mustang's platoon begins their attack on Central Command. He gives rather harsh orders, caring only about the outcome of the battle, commanding that all of the rebels be killed but Mustang (who still has to serve as a Human Sacrifice), gives permission to shoot Mrs. Bradley if need be and prepares an order to fire on the civilian residential area outside the Central Command gate. He is eventually captured by the soldiers from Briggs led by Captain Buccaneer and held hostage in Chapter 96 just before he could order a counterattack on the Briggs Tank full knowing that there were civilians nearby.

Fully aware of Father's plans, Klemin becomes erratic once the eclipse arrives and he is still being held captive; he begs his captors to "put him at the center" or else he will die. Klemin's soul is one of the millions absorbed by Father at the climax of The Promised Day, but thanks to the efforts of Van Hohenheim, he is brought back to life very much confused for what's happened.

After the Final Battle, he and Brigadier General Edison are the only surviving members of Central Command (not counting Olivier Mira Armstrong as she defected from them during the battle). Both are arrested and blamed as the mastermind on trying to destroy the entire population of Amestris through an alchemical experiment.

Trivia

 * Despite his name being "Klemin" in the manga published by Viz Media, in the anime adaptation dubbed by the Funimation, he is referred to as "Cremin".
 * His name could also be seen as ironic, as clemency is another word for "merciful", something that General Klemin definitely is NOT (especially when he orders the squad to fire on a civilian sector regardless of the harm to innocents that would almost inevitably follow).