Favorite characters added to already existing shows

[SFK]

I know! It's a shame they got that little boy fired. He was hilarious on The Cosby Show.

[reallyhateskateonlost]

Frank on LOST

[Huntress]

– Valerie Malone on "Beverly Hills, 90210"

– Audrey Liddell on "Dawson's Creek" (she was basically the only good thing about seasons 5 and 6)

– Kimberly and Sydney on "Melrose Place"

– Taylor Townsend on "The O.C."

– Lexie Grey on "Grey's Anatomy"

– Karen McCluskey on "Desperate Housewives"

– Deb on "One Tree Hill"

– Simon Elder and Nola Lyons on "Dirty Sexy Money"

– Lenore on "Hung"

– Shae and Margaery on "Game of Thrones"

[Gray Bunny]

Dana Delany to Desperate Housewives in season 4(?); Vanessa Williams in season 7.

[amybrickwallace]

Natalie Teeger on Monk.

[quartermainefan]

Sue Ann Nivens on MTM

[edgeofnik]

Fun Fact - Betty White only appeared in 42 out of 168 (that's only 25% of the run - yet such a memorable character!)

One of my favorite all-time quotes: Sue Ann just finished a show on cheese and she's passing around a platter. She offers Mary some cheese, but Mary balks.

SueAnn: "Oh, c'mon Mary, you'll love it. One of the cheeses is bland, American, untouched by human hands, not unlike you!"

I'll add:

Knots Landing - Lisa Hartman, Kevin Dobson, William Devane, Nicollette Sheridan and, of course, Donna Mills!