"I'll kill them all! I'll wipe every one of them... off the face of this earth!"
The main protagonist of Attack on Titan. He lived a peaceful life in Shiganshina District with his now late parents Grisha and Carla Yeager, and his adoptive sister Mikasa Ackerman, until the town was destroyed by Titans during the fall of Wall Maria.
After witnessing the death of his mother at the hands of the Smiling Titan, he vowed to wipe out all Titans in revenge. He joined the 104th Trainees Squad along with Mikasa and his childhood friend Armin Arlert, graduating as the 5th best soldier, and is currently a member of the Survey Corps.
He is also a person with the ability to transform into a Titan and the current holder of the power known as the Coordinate. (shingekinokyojin.wikia.com)