How about it? My candidates include:
Archie Bunker
Tim Taylor, Home Improvement
Harry Solomon, 3rd Rock from the Sun
Joey Gladstone, Full House
Larry Mondello, Leave It to Beaver
Fred, Baretta
Aunt Esther, Sanford and Son
Klem Kadiddlehopper, The Red Skelton Show
Howard Borden, The Bob Newhart Show
Ralph Malph, Happy Days
Angel, Rockford Files
Dopers, please post more. 
Latka Graves (Taxi)
Simka Graves (Taxi)
Revrend Jim Ignitousky (Taxi – boy did that show have some GREAT characters)
If I think of more later, I’ll post 'em.
Zev Steinhardt
Martin, My Favorite Martian
Julio, Sandford and Son
Mr. Bentley, The Jeffersons
Bull, Night Court
Norm, Cheers
Tim Conway’s businessman character, Carol Burnett Show
No one was ever nuttier than Lucy.
Blackadder
Baldrick
The Doctor (Who? 
)
That would be Mr. Tudball.
Cosmo Kramer, Seinfeld
Yes! Yes, it would. Thanks Mr. Arm.
And I’d like to add:
Harry Mudd, Star Trek
Lurch, The Addams Family
Jean/Gene, Quark
I’ll nominate Mr. Bean, second Cosmo Kramer and gives nods to both Ryan Stiles and Dieter Forgothislastname from the Drew Carry Show.
Ryan Stiles as Lewis Kiniski
Diedrich Bader as Oswald Harvey
Al Bundy, Married With Children.
Homer Simpson, The Simpsons.
Lionel Hutz, The Simpsons.
Bender, Futurama.
Mr. Garrison, South Park.
For goodness sakes, how can you not include Erkel on this list??
Basil Fawlty
I was fond of Redd Foxx on Sanford and son.
“Here I come, Elizibeth!”
Gracie Allen in the Burns and Allen Show. When the elevator operator said, “Down?” she pointed and said, “It’s that way.”
Bullwinkle J. Moose
Maxwell Smart
Carter “Captain Nice” Nash
Moose in “The Hot L Baltimore”
Det. Dietrich, Barney Miller
Rerun, What’s Happening!! (that’s not over enthusiasm, the title had 2 exclamation points)
Larry, Newhart
Mr. Carlin, Bob Newhart Show
Father Dougal Maguire on Father Ted
Father Jack on Father Ted
Mrs Doyle also on Father Ted
David Addison, Moonlighting
Multi-person tie between Dan Rather, Peter Jennings, Ted Koppel, and so on. I think it’s so wacky how they can say stuff like “four hundred people died in a jet crash” or “death toll from the earthquake is at least twenty thousand” in exactly the same tone of voice they say “Al Gore held a press conference at a meat-packing plant today” or “a new panda was born at the National Zoo.” Crazy, man, crazy.
the Cat (from “Red Dwarf”)
Edina Monsoon (from “Ab Fab”)
Pee-Wee Herman
Gomez Addams
Herman Munster
Adam (from Northern Exposure)
From “SNL” –
The Coneheads
Lisa Loobner
Mr. Robinson (as in "Mr. Robinson’s Neighborhood)
Bu’wheet (Buckwheat)
the Sweeney Sisters
Subliminal Ad man
the Church Lady
From “the Simpsons” –
Comic Book Guy
Bumblebee Guy
Apu
Lionel Hutz
From “Twin Peaks” –
Log Lady
the Little Man from another place
and lastly,
From “Northern Exposure” –
Marilyn (all-time BEST t.v. character ever!)
Adam & Eve
Honorable mention for Maggie’s long string of boyfriends who die in bizarre fashions.