Robin Williams, not a winner of Mark Twain Prize. (Carol Rosegg)

Lately the emphasis has been on “popular.”

By selecting Will Ferrell for the prize this year and Tina Fey last year, the Kennedy Center has favored youth and contemporary popularity (which certainly boosts TV ratings) over lifelong achievement. No knock on Ferrell and Fey. It’s just that they haven’t been around very long — at 43 and 40 years old, respectively, they’re the youngest ever selected.

If that’s the new standard, a few comic giants may be seeing their chance of winning the prize blowing up like a cheap cigar.

Here’s a short list of worthy, would-be Twain recipients who may have aged out of the running:

Robin Williams, 59

Jerry Seinfeld, 57

Joan Rivers, 77

Phyllis Diller, 93

David Letterman, 64

Jerry Lewis, 85

Don Rickles, 85

Larry David, 63

Garrison Keillor, 68

Steven Wright, 55

Robert Klein, 69

Woody Allen, 75

Mike Nichols, 79

Mary Tyler Moore, 74

Carol Burnett, 78

Betty White, 89

Dave Barry, 63

James L. Brooks, 71

Andy Griffith, 84

... and here are the past Mark Twain Prize winners:

Tina Fey

Bill Cosby

George Carlin

Billy Crystal

Neil Simon

Steve Martin

Lorne Michaels

Lily Tomlin

Bob Newhart

Whoopi Goldberg

Carl Reiner

Jonathan Winters

Richard Pryor

Imagine you could nominate a Mark Twain prize winner with a longer comedic track record ...

More on this story:

Will Ferrell, man of many impressions, tapped for Twain Prize
Straight man: Will Ferrell tackles drama
Photos: The many faces of Will Ferrell
Photos: Tina Fey wins 2010 Mark Twain Award