Tonight while watching the pilot episode of The Wonder Years, I spotted a familiar face as Kevin's first gym teacher. "Of course, we didn't realize it at the time, but this guy had the biggest inferiority complex since Napoleon." I haven't seen enough of the show to know if he's a regular or not, but what little I saw was stellar. Not sure if we're allowed to link to YouTube videos of this type, even though the show isn't available on DVD, but...it's there, and he shows up in part 2. "Suddenly, it became very clear why Mr. Cutlett had never been married..."
He had a recurring role for the first few years, from what I remember of the series, but never a regular.