Best ensemble cast?

Both Justified and Shield have amazing casts but the stories are so central to Vic and Raylan that I don't know if they qualify for the original premise.

For comedy shows with a "main" character I think Roseanne had a great cast

 

Hill Street Blues, like LTL said.

Soap, a terrific ensemble comedy classic.

Olders:
Mary Tyler More Show.
Dick Van Dyke Show
Carol Burnett Show.

 

Well if Justified & The Shield don't fit the original premise, Homicide: Life on the Street should. It had a regular cast that included Andre Braugher, Yaphet Kotto, Richard Belzer, Clark Johnson, Kyle Secor, Melissa Leo, Reed Diamond, Peter Gerety, Isabella Hofmann, Max Perlich, Daniel Baldwin and Ned Beatty.

 

The Office
Parks and Rec

 

I'd add "Law & Order" into the discussion, for which you could pick from several casts.

 

Agreed on M*A*S*H and ER, to go with The West Wing.

 

LA Law, from the way back...

Friends really stands out.

 

Don Knotts, Frances Bavier, George Lindsey, Jim Nabors, Ronnie Howard, and Howard McNear were all thespian talents equal to Andy Griffith. And that's not to mention the other regulars on the show like Helen, Ellie, Thelma Lou, Mayor Pike, or special appearance characters like The Darlings and Ernest T. Bass

And I don't see how one can say that Andy was the focal point of every episode. Barney's sidecar. Aunt Bea getting drunk off snake oil. Opie and the bully. Floyd's rich girlfriend. That show had it all. Andy played the straight man but he wasn't the focal point. He was sort of the tour guide to all of the rest of the incredible talent on the show.

 

WKRP in Cincinnati

Two very attractive pairs of boobs on that show too.

 

St. Elsewhere.

Mark Harmon
Denzel Williams
David Morse
Ed Flanders
Stephen Furst
Ronny Cox
Ricky Schroeder
Bruce Greenwood
Alfre Woodward
David Birney
Helen Hunt
William Daniels
Ed Begley Jr.
Howie Manzel
Norman Lloyd

Tremendous talent and a truly great show.

 

It's one of my favorite shows and I absolutely agree that the entire cast is fantastic, but I don't know it really falls into the ensemble category. It's Olyphant's show and the A-plot in every episode revolves around Raylan.