Carl Kasell, an NPR newscaster who, late in his career, cast off his anchorman gravitas once a week and for years became an absurdist comedian on the popular satirical quiz show “Wait Wait … Don’t Tell Me!,” died on Tuesday in Potomac, Md. He was 84.

His wife, Mary Ann Foster, said the cause was complications of Alzheimer’s disease.

To anyone who ever wondered what a radio personality was really like behind the disembodied baritone dignity, Mr. Kasell (pronounced KASS-uhl), gave it away in 1998 when he suddenly dropped the rock-steady mid-Atlantic voice of authority that millions had come to know over his decades as an éminence grise on public radio’s “All Things Considered” and “Morning Edition.”

In its place was a whimsical, charming North Carolina comic doing goofy impressions of Henry A. Kissinger, Britney Spears, Lindsay Lohan and others in the news. A voice that had been likened to that of America’s most trusted broadcaster, Walter Cronkite, was now concocting puns, singing falsetto jingles and joking about his comedown — from a radio kingpin to a comic making up voice-mail greetings as game-show prizes.

Mr. Kasell’s improbable second career, as “official judge and scorekeeper” of the news-related, call-in comedy hour “Wait Wait,” began when he was 64 and still working as an NPR newscaster. In what he regarded as his weekend gig, he played a sly, deadpan straight man to the show’s host, Peter Sagal, who quizzed contestants on the week’s dumbest events and most misguided newsmakers.