Reiner Braun is a prominent character in the anime series 'Shingeki no Kyojin' (Attack on Titan). He is initially introduced as a member of the 104th Training Corps and later becomes a squad leader in the Survey Corps. Reiner is known for his strong physique and leadership abilities. However, it is eventually revealed that he is the Armored Titan, a warrior sent by Marley to infiltrate the walls. His dual role as both ally and enemy creates a complex character torn between duty and friendship, making him central to the series' conflict.