Callan Grayne was a Human male who served in the Republic Army during the Great Galactic War with the Sith Empire, and later became a general in Republic Strategic High Command during the subsequent Cold War. As the Galactic War broke out with the Empire at the end of the Cold War, Grayne was sent to the icy planet of Hoth to take charge of the Republic offensive there. While coordinating the Republic Military on the planet, Grayne enlisted the aid of the Jedi Knight known as the Hero of Tython, and later assigned Sergeant Fideltin Rusk to the Jedi on the order of fellow High Command member Durant.