Two that stand out are Urkel from Family Matters and Sophia from The Golden Girls.

The Fonz. :D

The Fonz. :D

Drat, You beat me by one minute with that one. :D

Michelle on Full House. Not sure if that totally counts...

Michelle on Full House. Not sure if that totally counts...

I guess that depends on other people's opinions

What about the meathead from All In the Family? Does that count?

Fonzie on "HAPPY DAYS"

Vinnie Barbarino on "Welcome Back Kotter"
Will, the Robot and Dr. Smith on "Lost In Space"

Klinger and Father Mulcahy were considered "minor" characters in the early days of M*A*S*H, thier names not appearing until the end credits.

But over time, they became part of the regular ensemble, and Jamie Farr and William Chritsopher's names were placed in the opening credits with the other stars of the show.

Klinger was originally supposed to be on only one episode, but they kept brining him back for more episodes, and eventually he became a full fledged member of the cast.

Oh yeah, that reminds me. That was how it was with Marla Gibbs as Florence in The Jeffersons, she too had a minor role on the show.She didn't become a full fledged member of The Jeffersons cast until the 3rd season.

If you count spin-offs:

Gomer Pyle (THE ANDY GRIFFITH SHOW)
Fish (BARNEY MILLER)
Flo (ALICE)
Enos (THE DUKES OF HAZZARD)
Yogi Bear (HUCKLEBERRY HOUND)
Bullwinkle (ROCKY & HIS FRIENDS)

Yeah, you both beat me on the Fonz. They were thinking about changing the name of the show's title to "Fonzie's Happy Days" but thank god they didnt. I'm glad with just Happy Days.