Carl Sagan

Addams Family? Munsters? Those are obvious. But that's what came to mind.

Malcolm Reynolds from Firefly

When I was "growing up" NOBODY would have dared be a non-believer, or at least say it. That was the days of Romper Room, Mickey Mouse Club, Roy Rogers, The Lone Ranger, I Love Lucy. They may not have talked about religion during the program but you "just knew" they were believers.

George Carlin and penn and teller.

On this side of the pond it isn't quite the same issue but I suppose Dave Allen was obviously questioning/ridiculing the whole religious thing especially given his Catholic upbringing.

Mulder on the X-Files when I was in High School, is the only one I can remember seeing.

Meathead AKA Michael Stivic on"All in the Family."

Today? Brian Griffin. (The dog) Which Seth MacFarlane does in his own voice. So----Seth MacFarlane.

As a Brit, I can remember Terry Wogan on telly all the time when I was younger. I always thought he was an Irish Catholic, and nominally he was. However, in an interview on BBC a few years before he died he disclosed that he no longer believed there was a god. I always liked him anyway, but he rose several notches in my eyes then.

Good question, let's see. Kaine from Kung Fu my Buddhist Period, Spock I doubt he was, not sure about Captain Kirk?, Sean Leuc Picard, Carl Sagan, Einstein.Likewise Hawkeye Pierce. Mulder of course and that about takes me through to Uni years.

Probably George Carlin and Carl Sagan...as others have said. More recently though Ricky Gervais.

Doctor Who as he was always annoyed with anyone with ridiculous religious delusions, most of the original Star Trek crew (I was deinitely disappointed in Ohura when she got all sappy at the end of the episode Bread and Circuses), Carl Kolchak the Nightstalker didn't seem to be a believer but did go in for the ritual superstition connecting religion and monsters. Rod Serling seemed to be beyond religion as host of The Twilight Zone.
My all time favourite Star Trek atheist would have to be 7 of 9, even though she did believe in the Borg collective.

The first time I ever heard the word "agnostic" was from Mike Stivic on "All in The Family".

We all have forgotten a big one Bill Maher

George Carlin in the only one I can think of. Maybe Carl Sagan.

Family Guy has a few, Sheldon from Big Bang is current but most of my tv didn’t talk religion so you only knew if a character WAS not if they were not.

Two of my favorites - watched all of their shows. Also Bill Maher.

Sorry this is off topic but your reference to Dr Gregory House reminded me of his A Bit of Fry and Laurie days and you can see he was hedging his religious bets here.......

Dave Allen (UK tv) He'd always finish his show with "May your god be with you"

superman

None when I was growing up (that was too long ago) but I can still remember how I nearly swallowed my tongue when the security chief on Babylon 5 casually revealed that he was an atheist. And I was in my 40s at the time.

The first nonbeliever I can remember from TV--Michael Stivic from still my favorite sitcom ever, All in the Family.

Here is another good one Temperance Brennan

The robot on Lost in Space, The Jetson's etc. Many shows that didn't reference were open to suspicion. lol.