All Might is the No. 1 Hero and the "Symbol of Peace."

In his hero form, All Might is a very tall and over-musculated man whose design resembles the American hero comics. His hair spikes on top of his head and his whole body has more shadows than a normal human being.

However, in his true form, he is an over-skinny man who spits a lot of blood out of his mouth and his clothes appear wider.

(Source: Boku no Hero Academia Wikia)