On February 1, 1982, viewers tuning in to the premiere of the NBC show “Late Night with David Letterman” were greeted by the unsettling visage of an actor who came to be known as Larry “Bud” Melman. In an oddly nasal voice, he warned, “Certain NBC executives feel it would be unkind to present this show without a friendly word of warning.”

Mr. Letterman rocketed to late night fame, and Melman, played by Calvert DeForest in what was essentially his only professional role, remained part of the stable until he retired in 2003.

DeForest, who died Monday at 85, was a Brooklyn native whose seemingly loopy incomprehension and utter lack of acting skills played well in Mr. Letterman’s gonzo skits. Over two decades, DeForest introduced himself with a stone-faced lack of irony as Neil Diamond, Bob Dole, Barbra Streisand, and Roy Orbison, whom he really did resemble. He dressed as a chicken and as a bear. He was hurled through a foam-rubber mockup of the Berlin Wall and undertook a private goodwill tour to Mexico (which ended early after he begged Mr. Letterman on air to be allowed to come home).

Obviously reading off cue cards in a quavering monotone, he stepped all over Mr. Letterman and violated every rule of comic timing. Said Mr. Letterman, “If he ever gets good, he’ll be of no use to us.”

Perhaps the strangest fact about DeForest is that he really did aspire to be an actor. Raised in Bay Ridge, he attended Poly Prep High School. An uncle was radio pioneer Lee DeForest, and his father was a physician. DeForest never married and lived with his mother, a sometime stage actress, until her death, in 1959.

His uncle was a grizzled vaudevillian and veteran of silent films whose admonitions about how tough showbiz could be only egged on young DeForest. His mother forbade him to pursue acting, and except for a few sallies into summer stock, he obeyed her dictates.

“If she were living today, I wouldn’t be on television,” DeForest told People magazine in 1994. “She’d say, ‘You know, the door works both ways. If you want to leave, get out.’ And I was at a stage in life where I wasn’t able to fend for myself, so I stayed.”

He worked for many years as a file clerk at a New Jersey pharmaceutical company, Parke-Davis. He appeared occasionally in student and other low-budget films, where Mr. Letterman’s staff spotted him. He later called his first appearance on the show “the greatest thing that had happened to me in my life.”

By then, DeForest had been reduced to working as a part-time receptionist at a Queens drug rehabilitation center. A couple of years after he started working on “Late Night,” the rehab job boss fired him for exceeding its outside income restriction. “It was a blow, the way he did it,” DeForest told the New York Times in 1984. “They wouldn’t even let me finish out the week.”

DeForest became a minor icon on Mr. Letterman’s show, part of a goofy crew that included bandleader Paul Schaeffer and Chris Eliot in various manic guises. “Stupid Pet Tricks” and Mr. Letterman’s nightly top 10 list became cultural bywords. Gleefully mercenary, DeForest became a sub-celebrity spokesman for MC and Cheerios, in addition to such phony products as “toast on a stick.” He marketed a couch-potato workout and a book of bathroom humor, and hosted a Web site that branded Web surfers who clicked on it “suckers.”

In 1993, when Mr. Letterman moved to CBS from NBC, he was forced to leave the “Larry ‘Bud’ Melman” character behind as intellectual property. But Mr. Letterman brought DeForest along, henceforth identifying him by his given name. DeForest kicked off the very first episode of “The Late Show with David Letterman,” appearing in place of the circle in the network’s eye logo and squawking, “This is CBS!”

Calvert DeForest

Born July 23, 1921, in Brooklyn; died March 19 at Good Samaritan Hospital in Babylon after a long illness; there are no known survivors.