The other Principal Skinner. My kids and I watched that episode last night and there are some funny moments and I think the idea of uptight Skinner being a motorcycle punk in Capital City is great, but it just wrecks the whole dynamic of the Skinner character.
I don’t hate any of the other characters you’ve mentioned. They’re all fairly one-note, but they’re funny side characters. Otto has had some great moments like jamming on Bart’s guitar or describing Homer having a chicken wing on his face during his driver’s test.
There are a number of secondary characters all tied for last place. I’d put Crazy Cat Lady, Hans Moleman, and the Music Teacher in that category. Ralph is pointless but part of a team with the Chief. Otto is an important character, he had a number of important parts in episodes. Cletus was just the central character in an episode, a fairly good one in comparison to episodes this century. I’m not sure about Comic Book Store Guy, his store is important to have, he useful in comic book based episodes, but really doesn’t add much, and is pretty insulting to all the overweight lonely comic book store owners. I’ll add Disco Stu to the last place list, his lusting for Marge doesn’t add anything, Moe and others do that job just fine.
Of characters who are a) recurring and b) have some defined personality (rather than being one-note joke machines, like the Sea Captain, or specific celebrity stand-ins like Rainier Wolfcastle), I’ll say my least favorite is Reverend Lovejoy. Except for the end of the one episode that primarily features him (though Marge is, in large part, the focus), he just seems to not at all care about anyone or anything. His monotone makes him not only a poor joke-deliverer, but even a poor straight man. He serves a purpose, but given how much he appears in The Simpsons, could have become a much better character.
As I understand it Disco Stu was supposed to be just a one off joke. For his introduction, the Simpson family was holding a yard sale. Homer’s trying to sell an old jean jacket on which he’d attempted to write “Disco Stud” on the back in rhinestones, except he ran out of space. Marge remarks “Who would want a jacket that says ‘Disco Stu’ on it?” Cue Disco Stu. That was supposed to be the character’s sole appearance, but apparently he proved popular so they brought him back in later episodes.
I like Ralph Wiggum. As Nancy Cartwright once described him, Ralph is a walking non-sequitur.
The Sea Captain is pretty much a one note character, but I liked how they actually gave him a backstory in one episode this season. Of course they’re probably never going to mention it again.
I think I have to agree with Darren Garrison and pick Gil as my least favorite. It seemed like they introduced him to replace Lionel Hutz (who was retired after Phil Hartman’s death), but he is a poor substitute.
My favorite Disco Stu joke was when they Simpson-ized the “Odyssey” and he was one of the suitors for Marge during Homer/Odysseus’s absence as “Discus Stu”.
Duff-Man is basically Disco Stu but even more one-note, and I always felt his introduction wasn’t even funny unlike Disco Stu.
The Christmas Grumple is another one note character who had a terribly unfunny first appearance and then just kept coming back as a background character.
[slight hijack] A number of years ago, I read a book called “A Confederacy of Dunces”. As I’m reading, I started “hearing” the main character speak with the Comic Book Guy’s voice.
Turns out that the character Comic Book Guy was actually based on Ignatius J. Reilly.
[/hijack]