He was 65.

Mr. Pryor, who had been ill with multiple sclerosis, suffered a heart attack and died at a hospital in Los Angeles, his wife, Jennifer L. Pryor, told CNN.

His health had been in decline for many years.

Episodes of self-destructive, chaotic and violent behavior, often triggered by drug use, repeatedly threatened his career and jeopardized his life.

“Couldn’t escape the darkness,” he acknowledged, but he was able to put his demons at the service of his art.

Mr. Pryor’s brilliant comic imagination and creative use of the blunt cadences of street language were revelations to most Americans.

He did not simply tell stories; he brought them to vivid life, revealing the entire range of Black America’s humor, from its folksy rural origins to its raunchier urban expressions.

At the height of his career, in the late 1970’s, Mr. Pryor prowled the stage like a restless cat, dispensing what critics regarded as the most poignant and penetrating comedic view of African-American life ever afforded the American public.

He was volatile yet vulnerable, crass but somehow still diffident and anxious, and he could unleash an astonishing array of dramatic and comic skills to win acceptance and approval for a kind of stark humor.

“Pryor started it all,” the director and comedian, Keenen Ivory Wayans, said. “He made the blueprint for the progressive thinking of Black comedians, unlocking that irreverent style.”

For the actor, Eddie Murphy, Richard Pryor was, simply, “better than anyone who ever picked up a microphone.” The playwright, Neil Simon, called him “the most brilliant comic in America.”

Mr. Pryor’s body language conveyed the ambivalence (at once belligerent and defensive) of the Black male’s provisional stance in society. His monologues evoked the passions and foibles of all segments of black society, including working-class, churchgoing people and prostitutes, pimps and hustlers.

He unleashed a galaxy of street character who traditionally had been embarrassments to most middle-class Blacks and mere stereotypes to most whites, and he presented them so truthfully and hilariously that he was able to transcend racial boundaries and capture a huge audience of admirers in virtually every ethnic, economic and cultural group in America.

In 1998, he received the Kennedy Center’s first award for humor, the Mark Twain Prize, whose winners since have included Whoopi Goldberg, Bob Newhart and, this year, Steve Martin.

Mr. Pryor also won five Grammy Awards for his comedy albums.

His crossover appeal derived largely from his innovative approach to comedy (what Rolling Stone magazine called “a new type of realistic theater.”

It was, essentially, comedy without jokes (re-enactments of common human exchanges that not only mirrored the pretensions of the characters portrayed but also subtly revealed the minor triumphs that allowed them to endure and even prevail over the bleak realities of everyday living).

“Comedy,” he said, “is when you are driving along and see a couple of dudes and one is in trouble with the others and he’s trying to talk his way out of it. You say, ‘Oh boy. They got him,’ and you laugh.

“I cannot tell jokes. My comedy is not comedy as society has defined it.”

In his autobiography, “Pryor Convictions,” written in 1995 with Todd Gold, he allows Mudbone, the down-home raconteur who was perhaps his most unforgettable character, and, in many ways, his alter ego, to comment, “the truth is gonna be funny, but it’s gonna scare…folks.”

In fact, Mr. Pryor’s often harsh observations and explicit language did offend some audiences, but he insistently presented characters with little or no distortion.

“A lie is profanity,” he explained. “A lie is the worst thing in the world. Art is the ability to tell the truth, especially about oneself.”

Richard Pryor, the only child of Leroy Pryor and Gertrude Thomas Pryor, was born in Peoria, Ill., on Dec 1, 1940, and raised in a household where, as he wrote, “I lived among an assortment of relatives, neighbors, whores and winos, the people who inspired a lifetime of comedic material.”

His parents and grandmother ran a string of bars and bordellos that catered to transients who moved through the town, which was such an important stop on the Black and white vaudeville circuits that it inspired the expression, “Will it play in Peoria?”

A frail child, he learned how to use his quick wit and belligerent humor to gain respect from street gangs and bigger, more aggressive peers, but the antic behavior that served him well in the streets did not translate to the classroom, and he was expelled from school in the eighth grade despite his obvious talent and intelligence.

During the remainder of his teens, he worked as a truck driver, a laborer and a factory worker, and then joined the army, where he served in Germany until he was discharged after stabbing another serviceman during a fight.

He returned to Peoria, married, became the father of a son, Richard Pryor Jr., and, inspired by television appearances of Redd Foxx and Dick Gregory, began performing in local nightclubs. In 1962, a variety act offered him a job as a master of ceremonies. Leaving his wife and child behind, he began touring, appearing at small Black nightclubs in East St. Louis, Cleveland, Chicago, Pittsburgh and Youngstown.

In 1963, after homing his craft on the “chitlin circuit,” Mr. Pryor decided t take a crack at New York. He felt ready to compete with the “big cats” and to try to emulate the success of Bill Cosby, the comedian he most admired.

Soon, he was appearing at Greenwich Village clubs like Café Wha? The Living Room, Papa Hud’s and the Bitter End.

Mr. Pryor made his national television debut on Rudy Vallee’s “On Broadway Tonight” in 1964.

He had, in his own words, “entered the mainstream,” presenting “white bread,” non-offensive humor that freely copied the styles of other comedians, particularly Mr. Cosby. He worked the Catskills resort hotels and opened for the singer, Billy Eckstine, at the Apollo Theater in Harlem.

Bigtime television appearances followed on “The Ed Sullivan Show” and Johnny Carson’s “Tonight Show.” Two years after his arrival in New York, he had a national reputation.

Despite his growing popularity, Mr. Pryor was frustrated.

“I made a lot of money being Bill Cosby,” he recalled, “but I was hiding by personality. I just wanted to be show businesses so bad, I didn’t care how. It started bothering me. I was being a robot comic, repeating the same lines, and getting the same laughs for the same jokes. The repetition was killing me.”

In 1967, Mr. Pryor stormed off the stage of the Aladdin Hotel in Las Vegas, shouting: “What am I doing here? I’m not going to do this anymore!”

In his autobiography, he recalled: “There was a world of junkies and winos, pool hustlers and prostitutes, women and family screaming inside my head, trying to be heard. The longer I kept them bottled up, the harder they tried to escape. The pressure built til I went nuts.” Despite resistance from club owners, booking agents and advisers, he began listening to those voices, developing new material during the next few years served straight from the Black experience, even embracing the street vernacular use of the word “nigger.”

His first comedy album, “Richard Pryor” (1967) revealed his new direction with such routines as: “I always wanted to go to the movies and see a Black hero. I figured maybe on television they’d have it: ‘Look, up in the sky! It’s a crow. It’s a bat. No, it’s Super Nigger. Able to leap tall buildings with a single bound. Faster than a bowl of chitins.’ ”

By 1970, he had gone underground to reassess his life and his comic approach.

When he returned to show business in Los Angeles, his comedy had changed radically.

After seeing his revised act, Mr. Cosby said: “Richard Pryor took on a whole new persona, his own. Richard killed the Bill Cosby in his act, made people hate it. Then he worked on them, doing pure Pryor, and it was the most astonishing metamorphosis I have ever seen. He was magnificent.”

Some of his new material appeared on his second album, “Craps (After Hours)” (1971), which was recorded at the Redd Foxx Club in Hollywood.

He boldly engaged sensitive racial topics, mocking police harassment of Blacks and exploring differences between white and Black sexual attitudes.

Although “Craps” is considered one of Mr. Pryor’s best comedy albums, initial sales were dismal. Even the Black audience for whom it was intended largely ignored it.

Mr. Pryor persisted, however, developing his act and building a new following by returning to the small Black clubs that he had abandoned with his initial success.

He also appeared at better-known and challenging spots like the Apollo in Harlem and more cutting-edge comedy clubs downtown like the Improv.

The routines developed on those dates provided material for his next album, “That Nigger’s Crazy” (1974), which surprised record-industry executives with its appeal to young whites as well as Blacks.

Despite its X-rating because of explicit language and sexual content, the record sold more than a half-million copies and won the Grammy Award for best comedy album of the year.

It was followed by another X-rated album, “…. Is It Something I Said?” (1975), which also went gold and won another Grammy.

Appearances on television furthered Mr. Pryor’s career.

He was a popular host on “Saturday Night Live” in 1975, and, two years later, he agreed to do a series of television specials for NBC.

Mr. Pryor’s impact was not limited to comedy performance on records and the stage. He wrote for Redd Foxx’s popular television series, “Sanford and Son,” and for “The Flip Wilson Show.” He also collaborated with Lily Tomlin on her television specials, receiving an Emmy Award for best comedy writing for “Lily” in 1974.

After returning from a trip to Africa in 1979, Mr. Pryor told audiences he would never use the word, “nigger,” again as a performer.

While abroad, he said, he saw Black people running governments and businesses, and, in a moment of epiphany, he said, he realized that he did not see anyone he could call by that name.

He appeared in 40 films during a career that began with “Busy Bodies” in 1969 and concluded with a role opposite his frequent co-star, Gene Wilder, in “Another You” in 1992.

His first starring role, in 1976, was as a racecar driver in “Greased Lighting,” and he co-starred with Mr. Wilder in “Silver Streak.”

Although he would dismiss “Silver Streak” as a “stupid film,” audiences loved his performance, and he became one of Hollywood’s hottest box-office draws.

Mr. Pryor probably reached the pinnacle of his career in 1979 with his first concert film, “Richard Pryor, Live in Concert,” filmed in Long Beach, Calif. It remains the standard by which other movies of live comedy performances are judged. The film, which was to inspire others to make their own comic performance movies, caught Mr. Pryor at peak form.

He reflected often about his own tumultuous life, with monologues about a domestic quarrel in which he shot his wife’s car, the death of his pet monkeys and a near-fatal heart attack, which ended with “I woke up in the ambulance. Right? There was nothing’ but white people starin’ at me. I say: ‘I done died and wound up in the wrong Heaven. Now, I gotta listen to Lawrence Welk the rest of my days.”

If he used his misadventures to earn fame and fortune, Mr. Pryor also frequently undercut his career and his life with his self-destructive behavior.

In 1974, for example, he was sentenced to 10 days in jail, fined and put on probation after pleading guilty to a charge of willful failure to file an income tax return.

In 1978, a court fined him $500, placed him on probation again and ordered him to seek psychiatric care and make restitution after a New Year’s Day incident, in which he rammed his Mercedes into a car containing friends of his wife and then shot at it with a pistol.

In 1980, after a drug binge, Mr. Pryor was critically burned in an explosion that police said was caused by the ignition of ether being used in conjunction with cocaine.

Paramedics found him walking in a daze more than a mile from his home outside Los Angeles with third-degree burns over the upper half of his body. He was hospitalized for almost two months while undergoing a series of skin grafts.

Recovering, Mr. Pryor remained a top box office attraction during most of the 1980’s.

He appeared in numerous movies and released two more films of live comedy performances, but he continued to be bedeviled by drug and health problems.

In 1986, he was found to be suffering from multiple sclerosis, a disease that strikes at the central nervous system, and, as the years passed, he experienced its cruelest symptoms: vertigo, tremors, muscle weakness and chronic fatigue.

His performances in “See No Evil, Hear No Evil” (1989) and “Another You” (1992 revealed a frail, hesitant actor.

Still, in 1992, he was back at the Comedy Store in Los Angeles polishing material for a concert tour. He was no longer able to stand onstage and he delivered his monologue from an easy chair, but he was forced to cancel his tour early the next year.

“I realized that I had more heart than energy, more courage than strength,” he said. “My mind was willing, but my feets couldn’t carry me to the end zone.”

Mr. Pryor was married six times and divorced five times.

In addition to his wife, three daughters, Rain Pryor, Elizabeth Pryor and Kelsey Pryor; and three sons, Richard Pryor Jr., Steven Pryor and Franklin Pryor, survive Mr. Pryor.