Theo Magath was the general of the Marleyan military, successor to General Calvi through the support of Willy Tybur and the governmental party of Marley.
Formerly a commander of the Eldian Unit of the Marley army, and before one of the chief overseers of the first Warrior candidates during their training, he later led the Eldian Warriors in the Marley Mid-East War against the Mid-East Allied Forces, playing a key role in Marley's victory.
Magath was an older man with light eyes and a thin beard, mustache, and black hair with a short buzz cut. He had visible wrinkles from age but an overall healthy build and appearance. Like his fellow soldiers, he wore the standard Marleyan soldier uniform consisting of a light jacket and pants with a black clip at the collar, supply packs on the hip, suspender straps, a hard hat with a black stripe around it, and tall combat boots.
Appearance: Magath was an older man with light eyes and a thin beard, mustache, and black hair with a short buzz cut. He had visible wrinkles from age but an overall healthy build and appearance.
Personality: Theo Magath was extremely dutiful, and most of his personality and choices revolved around what he believed was his duty as a soldier of Marley. Even though he, as a typical Marleyan, was prejudiced against Eldians, valuing the lives of the Marleyans above the Eldians and being angered when one questions his orders, he was willing to put his opinion aside and let the Eldians under his command speak, in case they might have something useful to add to the current situation, such as Colt Grice and Zeke Yeager.
History: While the details of his rise to power are unknown, Magath has been a member of the Marleyan military for over twenty years. Early in his career, Magath was considered one of the best artillerymen in the Marleyan military.
Theo Magath in the story: About four years after the failed Paradis Island Operation, Magath led an 800-Warrior unit against the Mid-East Allied Forces at the battle of Fort Slava. When the Warriors' trench line could advance no further towards the bunkers around the fort, candidate Colt Grice suggests to Magath that both the Jaw and Cart Titan should be used against the Allies. Magath refuses this suggestion, pointing out the Allies' anti-Titan artillery and the great risk of losing their Titans against it.
Source: Attack on Titan Wiki, available under CC BY-SA 3.0.