One of the four co-founders of Hogwarts School of Witchcraft and Wizardry. Godric Gryffindor valued bravery, and founded Gryffindor house. The Sorting Hat originally belonged to Gryffindor.
Warning: Spoilers Follow
In Harry Potter and the Chamber of Secrets, Harry Potter pulled a sword with Gryffindor's name on it out of the Sorting Hat. Albus Dumbledore said only a true Gryffindor could do that.