Growing up in the 90s, my first exposure to Mull was in StTW as the crotchety, vindictive, humorless, principal. The dude’s actually hilarious in just about everything else, and it took me a long time seeing him in other roles to shake the uptight principal image out of my head.
IDK, I really liked him as the Principal.
He wasn’t bad in the role, but he was definitely more of a foil / straight man / punching bag. Or, at least that’s how I’m remembering it, anyway. I just feel bad for having thought, “Wait, he can be funny?!” when I saw him in other roles later.