Probably the only good Defense Against the Dark Arts teacher that wasn't evil as shit. The stories of the class were a lot better than any other year in the book, and he taught Harry quite a bit of stuff like the Patronus charm.
He also kept quite a bit of role after he resigned from the job. Helping Harry in many battles and moments.
Sad to see him die at the end. JK Rowling left his son an orphan.