Sues died Thursday night while watching television at his home in West Hollywood, said Michael Gregg Michaud, a longtime friend.
As a cast member of "Laugh-In," the overnight sensation that debuted on NBC in 1968, Sues joined performers including Judy Carne, Goldie Hawn, Ruth Buzzi, Jo Anne Worley, Arte Johnson and Henry Gibson in the weekly hour of wildly wacky, fast-paced comedy.
During his time on the show from 1968 to 1972, Sues played the recurring characters Big Al, the effeminate sportscaster, who'd ring a small bell on his desk and exclaim, "Oh … my tinkle … my tinkle … I looove my tinkle"; and Uncle Al the Kiddies' Pal, the perpetually hung-over children's show host. ("Oh, Uncle Al had a lot of medicine last night, boys and girls.")
"Alan was a free spirit, an outrageous human being who was a love child," George Schlatter, the show's executive producer, told The Times on Friday. "He'd say things like 'a frown is just a smile upside down,' and he'd scold me if I ever got firm with the cast.
"He was a delight; he was an upper. He walked on the stage and everybody just felt happy."
One time, Schlatter recalled, Sues came out during a taping dressed as Worley — in full makeup, a wig, high heels and a feather boa.
"'Laugh-In' was a series of accidents," said Schlatter, "and Alan was one of my favorite accidents."
Buzzi said Sues was "the funniest person that I ever worked with."
"He was hysterically funny," she told The Times on Friday. "One time, the both of us were laughing so hard at something that he said that I was literally on the floor laughing."
During his years on "Laugh-In," Sues became the spokesman for Peter Pan Peanut Butter and appeared in numerous TV commercials and print ads in which he portrayed an outrageously flamboyant Peter.
Michaud said Sues was gay but not publicly because he feared it would ruin his career.
"He had a ton of gay fans," said Michaud. "They all said he was one of the very few gay sort of characters that they saw on television at that time. They identified with him, and they were thankful. As he got older, it meant more to him and he was appreciative of that."
Sues was born March 7, 1926, in Ross, Calif. and later moved to La Cañada-Flintridge, where his father bred racehorses.
An unauthorized visit to Paramount Studios as a teenager — he jumped a fence and watched a scene being filmed for the 1942 Bing Crosby movie "Holiday Inn" — was a turning point.
Sues, who served in the Army during World War II, studied acting at the Pasadena Playhouse and made his Broadway debut in 1953 as a boys' school bully in the long-running play "Tea and Sympathy."
He later had a song-and-dance comedy act that he and his then-wife, Phyllis, performed in nightclubs. Early in his career, he also played small roles in films such as "The Americanization of Emily" (1964) and appeared on TV series including "The Twilight Zone" and "The Wild Wild West."
In 1975, Sues returned to Broadway, taking over the role of Professor Moriarty in a revival of "Sherlock Holmes." After finishing the Broadway run in 1976, he did the national tour.
Sues more recently completed recording an audio collection of funny personal stories and show biz anecdotes that will be available on CD and sold on his website.
Sues is survived by two nieces and a nephew.