Walter Skinner became a fan favourite over the years, and it's no surprise that Mitch Pileggi is back for the revival as a result. In fact, he hasn't been absent from a season, or either of the movies, since he first joined the show late in season one, and was a main character (added to the credits) in the final year of the show. He also hasn't changed a bit, aside from sporting a beard with more than just a touch of grey. And interestingly enough, that makes him look even more distinguished, and just a bit more of an intimidating presence. Maybe he should have gone to this look sooner!