Erwin's father

Mr. Smith was the biological father of Erwin Smith. It was his words that motivated Erwin Smith to try to prove that his theory about the Walls was real.

Appearance
He was a tall old man with short hair, circular glasses, and an unkempt beard and moustache.

Personality
He seemed to be highly intelligent, considering how he theorized about the Walls. Also, he cared deeply for his son's future, so much that he did not reveal the "dangerous" theory in his history class for his sake and the students, but alter told Erwin.

History
Considering that he died even before Erwin Smith entered into the Survey Corps, he seemed to live much before when Eren Yeager was born.

Relationships

 * Erwin Smith - He trusted Erwin so much that he revealed his dangerous theory about the walls to him. But Erwin ended up telling the military police about the theory, which caused his death.