I'm not counting or accepting young children for this discussion because I felt that something like that (e.g. Cousin Oliver on The Brady Bunch as a prime example) would be too obvious.

http://www.lipstickalley.com/showthread.php?t=480818

The Andy Griffith Show:

Warren Ferguson
Howard Sprague
Emmett Clark

Dennis the Menace:

John & Eloise Wilson

Gomer Pyle USMC:

Lou Ann Poovie

Kay on Murphy Brown. Still wish they'd bury those episodes and never show them in reruns.

Living Single - Ira "Tripp" Williams

Martin - Shanise McGullicuddy

I'll list more as I think about them...

Bronson Pinchot's character whatever his name was on Step By Step.

Bronson Pinchot's character's name on Step By Step was Jean-Luc Rieupeyroux. I personally loved his character on the show- of course, I think all of Step By Step is great. (But it was particularly neat for me since I also am a big fan of Perfect Strangers and it was fun to see "Balki" in another role on another show that I like.):) :cool:

Speaking of Murphy Brown, McGovern. Thankfully she didn't last too long.

Designing Women - Allison Sugarbaker. It wasn't Julia Duffy's fault, but the writing was too cliched for her.

Everybody Loves Raymond - The entire cast. What I mean by this is the final seasons of the show, all the main characters were just downright nasty to each other and Debra got even more obnoxious and unlikeable. I had to quit watching.

Doctor Who - Rose Tyler, especially in her second year on the show. She went from a somewhat annoying but tolerable teenage girl to a really annoying, whiny, lovesick twenty-one year-old. Unfortunately she's one of the most popular characters in the show's history and a lot of fans haven't accepted anyone that's come after her which is a shame, because the later companions were 100X better than she was.