Bugs Bunny.
Ambassador Kosh.
James Kirk.
FBI Special Agent Dale Cooper.
Everyone else on Twin Peaks too.
Especially Albert.
Captain Mal.
I remember one where he was a cavalry officer, and another where he was the bad guy while Cheyenne was making moves on Angie Dickinson!
Many of my favorites have been listed.
here is a couple that I haven’t seen yet:
JR Ewing
Jackie Harris (Roseanne)
Eddie Haskell
Anita Van Buren
Church Lady (does she count?)
Ed Norton (The Honeymooners)
Data
Gregory House
Niles Crane
Cosmo Kramer
Carleton the Doorman
Adrian Monk
The Doctor (Star Trek: Voyager)
Ida Morgenstern
Sherman Potter
Lou Grant
Edith Bunker
Benjamin Linus
Marie Barone
Zelda Gilroy
Stephen Colbert
Zorro
Edit: Just read everybody else’s. HOW did I forget Eddie Haskell ?
The Stig
Kirk
Spock
McCoy
Scotty
Rob Petrie
Laura Petrie
Radar O’Reilly
Kim Possible
It was 50 years ago and I was a kid but I can remember some episodes like I saw them last night.
Sergeant Ernie Bilko and Ralph Kramden were the first TV characters I can remember as whole living people.
If you’re at all like I am, it’s difficult to come up with a definitive list of shows that featured “favorite characters” over the span of my TV viewing years. In my case that’s something like the period since 1952 or so – roughly 60 years!
For me the biggest problem comes from the “middle years” in that I have no real trouble picking out my favorites from the “early years” (back when I was a teenager and TV was new to me) nor from the “recent years” (let’s say the last 10 or so). It’s that big gap of at least 20 years ('70’s through '90’s, let’s say) when for whatever reason I’m just drawing a big blank on what TV was impressive to me in those days.
To try to jog my own memory I have started to look back at some older threads on SDMB where TV shows were the main issue to see if “favorite characters” will become obvious that way.
Here are a few of those threads:
================================================
Who are your FIVE (5) favorite characters from “THE WIRE”?
…and the best TV show in the history of the universe is:
The Best All-Time TV Show [vote for up to 10]
Your Favorite All-Time TV Shows - Cafe Society - Straight Dope Message Board
Your Favorite All-Time TV Shows
If you know of other such threads (that I must have missed) please provide links to them.
Xena
Buffy
Captain Tightpants
Jayne Cobb (well his big gun, really)
Meredith McKay 
Mr Spock
Samantha Carter
Uhura
Roger
Here are a few to add to the list:
Jesse Pinkman
Hank Schrader
Mike Ehrmantraut
Peggy Olson
Joan Harris
Titus Pullo
Atia of the Julii
Chloe O’Brian
Lt. Columbo (Columbo)
Rory Gilmore (The Gilmore Girls)
Jarod (The Pretender)
Veronica Mars (Veronica Mars)
Gaius Baltar (Battlestar Galactica)
Blair Waldorf (Gossip Girl)
Arvin Sloane (Alias)
Many of mine are already listed, but I will add:
Gomez Addams (as played by John Astin)
Dr. Tony Hill (from Wire in the Blood)
Nero Wolfe (as played by Maury Chaykin)
QE I (as played by Miranda Richardson - Blackadder II)
Good ones
Ron Swanson - *Parks and Recreation *
Hank Kingsley - The Larry Sanders Show
Dan Fielding - Night Court
Dan Conner - Roseanne
Barney Fife - The Andy Griffith Show
Claire Fisher - Six Feet Under
Federico ‘Rico’ Diaz - Six Feet Under
John Fitzgerald Byers - The X-Files/ The Lone Gunmen
A few more (can’t believe I forgot a couple of these):
Q, from Star Trek: TNG
Darlene Conner, from Roseanne
Doogie Howser, from Doogie Howser, MD
Methos, from Highlander
Detective Brisco, from Law and Order
Major Casey, from Chuck
The Doctor, from Doctor Who
Prof. Charlie Eppes, from Numb3rs
“Mr. Finch” and “Mr. Reese”, from Person of Interest
Agent Bill Maxwell, from The Greatest American Hero
Dr. Zoidberg, from Futurama
i’ll second ralph kramden and add:
-Spike (from the buffy/angel tv series)
Bill McNeal (Newsradio)
Ron Swanson (Parks&Rec)
Lillith Crane (Cheers)
Abed (Community)
Kay Howard (Homicide)
Frank Pembleton (Homicide)
Tim Bayliss (Homicide)
Willie Caine (Sandbaggers)
Neil Burnside (Sandbaggers)
Mike Wallace (Sandbaggers)
Titus Pullo (Rome)
Lucius Verinus (Rome)
Lennier (Babylon 5)
Elim Garak (Star Trek: DS9)
Simon Tam (Firefly)
Julian Bashir (Star Trek: DS9)
Mr. Spock (Star Trek)
Aeyrun Sun (Farscape)
Pa’u Zotoh Zhaan (Farscape)
Aang (Avatar: The Last Airbender)
Zuko (Avatar: The Last Airbender)
Katara (Avatar: The Last Airbender)
Toph (Avatar: The Last Airbender)
Albert Rosenfeld (Twin Peaks)
Eddie Haskell
Chief O’Hara
Mr. Spock
Mr. (Elliot) Carlin