Jonathan Winters, once described by “Tonight Show” host Jack Paar as “pound for pound, the funniest man alive” and a comedian whose freeform work with multiple voices and personalities presaged the antics of comics such as Robin Williams, died of natural causes Thursday in Montecito, Calif. at 87.

A pioneer of improvisational standup comedy, with an exceptional gift for mimicry, a grab bag of eccentric personalities and a bottomless reservoir of creative energy, he was introduced to millions of new fans in 1981 as the son of Williams’ goofball alien and his earthling wife in the final season of ABC’s “Mork and Mindy.” He appeared in numerous films including “It’s a Mad Mad Mad Mad World” and did extensive voice work on toons including “The Smurfs.”

Born Jonathan Harshman Winters III in Dayton, Ohio, Winters was raised mostly by his divorced mother, a radio personality in Springfield, Ohio, and showed an early gift for mimicry. He served in the Marines in the Pacific during WWII, then attended Kenyon College and later the Dayton Art Institute. He held down a variety of jobs while seeking to become a cartoonist. After winning a talent contest, Winters landed a DJ gig at Dayton radio station WING, and he was soon ad-libbing freely on-air; for several years he hosted some local programs for Columbus TV station WBNS, but in 1953 he headed for New York.

Winters played comedy clubs in Manhattan and did early live TV. In 1954, he was cast as a regular on the NBC comedy-variety series “And Here’s the Show,” and he was a contestant, with many other rising performers, on “Arthur Godfrey’s Talent Scouts,” which led to a featured spot in the 1954 Broadway revue “Almanac.”

He also made many appearances on “The NBC Comedy Hour.”

By the late ’50s, Winters was guesting repeatedly on “The Jack Paar Tonight Show” (and later on “The Jack Paar Program”). Alluding to the many characters Winters portrayed in his act, Paar once said, “If you were to ask me the funniest 25 people I’ve ever known, I’d say, ‘Here they are — Jonathan Winters.’”

Winters also recurred on “The Steve Allen Show” and “The Garry Moore Show.”

During the late 1950s, however, Winters suffered at least one emotional breakdown and spent time in a mental hospital. He was later diagnosed with manic depression (now known as bipolar disorder) and medicated appropriately. In his standup routines he made obscure references to his illness and hospitalization. He was one of the first one celebrities to go public with a personal mental illness issue and felt stigmatized as a result. “This is something I’ve never quite shaken,” he once said. “There are bigger stars than me with all kinds of coke problems, sauce problems, guys that are married four, five times. Then they put them in picture after picture. Why should I have to go through my life auditioning and proving I’m sane?”

Whatever the extent or manner of his personal demons, Winters was able to harness them to bring an unprecedented frenetic energy to his work as a comic. He did not tell joke or rattle off punchlines but improvised on any subject. He also channeled his mania into a variety of characters including ribald old lady Maude Frickert, quack psychiatrist Dr. Bellenhoffer, Southern yokel Elwood P. Suggins and brash movie star Lance Lovegard.

During the early 1960s, Winters issued a slew of successful comedy albums: “Down to Earth” (1960), “The Wonderful World of Jonathan Winters” (1960), “Here’s Jonathan” (1961), “Another Day, Another World” (1962), “Humor Seen Through the Eyes of Jonathan Winters” (1962), “Jonathan Winters’ Mad, Mad, Mad, Mad World” (1963) and “Whistle Stopping With Jonathan Winters” (1964).

In 1961 the comedian exercised his serious side in a famous episode of “The Twilight Zone” called “A Game of Pool,” in which he played a dead pool great resurrected for a game with a player portrayed by Jack Klugman.

Two years later he made his bigscreen debut in the Stanley Kramer comedy “It’s a Mad Mad Mad Mad World,” appearing with an all-star cast of comics including Sid Caesar and Milton Berle.

In 1965 Winters was wasted in Tony Richardson’s surreal satire of the funeral industry “The Loved One,” scripted by Terry Southern based upon Evelyn Waugh’s novel. The next year he appeared in Norman Jewison’s cold war satire “The Russians Are Coming the Russians Are Coming.”

Winters was better served in 1969’s “Viva Max!,” a satire centered around the mythology of the Alamo, in which he played a general more interested in his thriving furniture business.

Meanwhile, sketch variety show “The Jonathan Winters Show” ran for two seasons on CBS in 1967-69 and syndicated comedy variety show “The Wacky World of Jonathan Winters” ran more briefly in the early ’70s; both prominently featured Winters’ characters, including Maude Frickert. He also guested repeatedly on “The Carol Burnett Show,” “The Smothers Brothers Comedy Hour,” “The Tonight Show With Johnny Carson” and, especially, “The Dean Martin Comedy Hour.”

Winters made his last major nightclub appearance in 1972 at the Hilton International in Las Vegas.

In 1976 the comedian penned and hosted the NBC special “Jonathan Winters Presents 200 Years of American Humor.”

Winters’ guesting gig as Mearth on “Mork and Mindy” gave Robin Williams, the star of the show, a chance to work with the comedian who had most influenced his work.

“Jonathan’s the source for me, the guy that made it all possible,” Williams once said. “He’s the Smithsonian, all these riffs he stores up. Just sit back and watch him. He’s a force of energy. Comedy would be more closed off without him.”

In 1985, Winters appeared as Humpty Dumpty in the CBS miniseries version of “Alice in Wonderland.”

During the 1980s Winters began to do a great deal of voicework for animated programs, including “The Smurfs” and NBC’s “The Completely Mental Misadventures of Ed Grimley,” an adaptation of Martin Short’s character from “Saturday Night Live.”

Winters was a series regular on the 1991-92 sitcom “Davis Rules,” playing Randy Quaid’s eccentric father, and he won the 1991 Emmy for supporting actor in a comedy series.

He guested on ABC sitcom “Life With Bonnie” in 2002 and earned a guest actor in a comedy series Emmy nomination.

Speaking of how he prepares as a comedian, Winters told interviewer Dan Pasternack in 2002, “You’ve got to study people. If you go to the Actors Studio fine; if you take lessons from someone, fine. There are all kinds of workshops and comedy stores and dramatic workshops, etc., but you must be an observer. You must look at everything around you.”

On the other hand, he said on another occasion that in doing comedy, “I’ve always had the most fun when I was improvising.”

Winters continued to do occasional bigscreen work into his mid-80s, appearing in the Paul Mazursky comedy “Moon Over Parador” in 1988, in “The Flintstones” in 1994 and “The Adventures of Rocky and Bullwinkle” in 2000. He had a role in “Cattle Call” in 2006 and voiced Papa Smurf in 2011 film “The Smurfs.”

Winters appeared in the PBS documentary series “Make ’Em Laugh: The Funny Business of America” in 2009 and guested on Showtime’s “The Green Room With Paul Provenza” in 2010.

He made more than a dozen comedy recordings in his career. Winters resumed issuing albums in 1988 after a 19-year absence and continued to produce them until 2011, when he released “Final Approach.” He received 11 Grammy nominations for his albums, and his disc “Crank Calls” won the Grammy for spoken comedy album in 1995.

Winters friend Jim B. Smith saved all of his 3,000-plus phone messages from the comedian over the years and published a selection of them in the 1989 book “Jonathan Winters… After the Beep.”

The comedian won the second Mark Twain Prize for Humor, presented by the Kennedy Center, in 1999.

In a tribute at the sixth Annual TV Land Awards in June 2008, Williams presented Jonathan Winters with the TV Land Pioneer Award, which honors performers who have distinguished themselves by pushing the frontiers of the media.

Winters’ wife of 60 years, Eileen, died in 2009.

He is survived by a son and a daughter and five grandchildren.

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