Phil Spector, one of the most influential and successful record producers in rock ’n’ roll, who generated a string of hits in the early 1960s defined by the lavish instrumental treatment known as the wall of sound, but who was sentenced to prison for the murder of a woman at his home, died on Saturday. He was 81.

The cause was complications of Covid-19, his daughter, Nicole Audrey Spector, said. He was taken to San Joaquin General Hospital in French Camp, Calif., on Dec. 31 and intubated in January, she said.

Mr. Spector had been serving a prison sentence since 2009 for the murder of Lana Clarkson, a nightclub hostess whom he had taken to his home after a night of drinking in 2003. The Los Angeles police found her slumped in a chair in the foyer, dead from a single bullet wound to the head.

Mr. Spector scored his first No. 1 hit when he was still in his teens. With the Teddy Bears, a group he formed with two school friends, he recorded the dreamy ballad “To Know Him Is to Love Him.” Released in August 1958, it sold more than a million records after the group appeared on the popular TV show “American Bandstand,” with Mr. Spector playing guitar and singing backup.

After learning the ropes as a record producer, Mr. Spector, the central figure in Tom Wolfe’s 1965 essay “The First Tycoon of Teen,” became a one-man hit factory. Between 1960 and 1965 he placed 24 records in the Top 40, many of them classics.

His 13 Top 10 singles included some of the quintessential “girl group” songs of the era: “He’s a Rebel,” “Uptown,” “Then He Kissed Me” and “Da Doo Ron Ron”by the Crystals, and “Be My Baby” and “Walking in the Rain” by the Ronettes.

For the Righteous Brothers he produced “Unchained Melody” and “You’ve Lost That Lovin’ Feeling,” a No. 1 hit that became the 20th century’s most-played song on radio and television, according to BMI.

Mr. Spector single-handedly created the image of the record producer as auteur, a creative force equal to or even greater than his artists, with an instantly identifiable aural brand.

“There were songwriter-producers before him, but no one did the whole thing like Phil,” the songwriter and producer Jerry Leiber told Rolling Stone in 2005. Mr. Leiber, who died in 2011, and Mr. Spector served a brief but crucial apprenticeship together at Atlantic Records.

Mr. Spector’s signature was the wall of sound, perfected at Gold Star Studios in Los Angeles, where he worked with the engineer Larry Levine, the arranger Jack Nitzsche and a team of musicians nicknamed the Wrecking Crew by Hal Blaine, one of their regular drummers.

With dozens of musicians and backup singers packed into Gold Star’s cramped quarters, Mr. Spector layered multiple guitars, basses and keyboards over one another and applied a shimmering gloss of strings. This sonic wave assumed even grander proportions when channeled through Gold Star’s resonant echo chambers.

“The records are built like a Wagner opera,” Mr. Spector told The Evening Standard of London in 1964. “They start simply and they end with dynamic force, meaning and purpose. It’s in the mind, I dreamed it up. It’s like art movies.”

The wall of sound profoundly influenced a host of producers and rock groups, from the Beach Boys to Bruce Springsteen.

“He was everything,” Brian Wilson of the Beach Boys told an interviewer for the British documentary “Endless Harmony: The Beach Boys Story.” He called Mr. Spector “the biggest inspiration in my entire life.” To John Lennon, he was “the greatest record producer ever.”

“He added a drama to music that I don’t think existed before him,” the record producer Jimmy Iovine told Rolling Stone in 1990. “Making dark records and pop records are separate things. When you can combine the two worlds, you’ve achieved greatness. He not only achieved it, he basically invented it.”

Harvey Philip Spector was born on Dec. 26, 1939, to a lower-middle-class family in the Bronx. His father, Benjamin, the son of Russian Jewish immigrants, was a union ironworker who committed suicide when Harvey was 8. (Mr. Spector hated his first name and went by Phil, adding an “l” to “Philip” as well.) The epitaph on his father’s tombstone, “To Know Him Was to Love Him,” found its way into Mr. Spector’s first hit.

His mother, Bertha, moved him and his sister, Shirley, to Los Angeles, where Bertha Spector worked as a seamstress and later a bookkeeper. After graduating from Fairfax High, he studied to be a court stenographer at Los Angeles City College.

After the Teddy Bears disbanded in 1959, Mr. Spector turned to producing and found a mentor in Lester Sill, who had helped Mr. Leiber and his partner, Mike Stoller, get started in the music business. Mr. Sill arranged for Mr. Spector to work with the two men at Atlantic Records, where their use of strings and heavy instrumentation became part of his repertoire.

While at Atlantic he played on sessions for the Coasters, LaVern Baker, and the Drifters. (He provided the guitar solo on the Drifters’ hit “On Broadway.”) He also helped write and produce Ben E. King’s hit “Spanish Harlem.”

He also produced two hit records on other labels, “Corinna, Corinna,” by Ray Peterson, and “Pretty Little Angel Eyes,” by Curtis Lee, a bland love song that he souped up by inserting the Halos, a Bronx doo-wop group, as backup.

Returning to Los Angeles, Mr. Spector worked with the Paris Sisters, a local trio, producing “I Love How You Love Me,” a feathery, echo-laden ballad with silky strings that rose to No. 5 on the charts.

Mr. Spector struck gold when he began working with the Crystals, a New York group that he signed to Philles Records, a label that he and the record executive Lester Sill created in 1961, fusing their first names. Mr. Spector bought out Mr. Sill a year later.

After “There’s No Other (Like My Baby)” and “Uptown” reached the Top 20, Mr. Spector was keen to have the Crystals record the Gene Pitney composition “He’s a Rebel” immediately. To speed things along, he enlisted the Blossoms, a well-known Los Angeles backup group, and recorded them under the Crystals name, with Darlene Wright (whose last name he changed to Love) on lead. The record became Philles’s first No. 1 hit.

Mr. Spector shuffled his singers at will. He drafted Ms. Love and another Blossom, Fanita James, to sing with Bobby Sheen on one of his more idiosyncratic hits, “Zip-a-Dee Doo-Dah,” credited to the group Bob B. Soxx and the Bluejeans. For the singles “Da Doo Ron Ron” and “Then He Kissed Me,” he re-enlisted the original Crystals, now with a new lead singer, the 15-year-old Dolores Brooks, known as LaLa. Both songs made the Top 10.

The Crystals, along with the Ronettes and Ms. Love, all performed on “A Christmas Gift for You From Phil Spector,” a collection of holiday songs. The album, now regarded as a Spector masterpiece, was released the day of the Kennedy assassination in 1963. Mr. Spector withdrew it from sale, and it sank without a trace.

With the Righteous Brothers, the wall of sound assumed towering heights, but Mr. Spector surpassed himself when he put Tina Turner in the studio in 1966 to record “River Deep, Mountain High,” which employed 21 musicians and an equal number of backup vocalists.

The record rose to the upper reaches of the British charts but flopped in the United States. Dismayed, Mr. Spector withdrew from the music business for several years and entered a decades-long decline marked by erratic behavior, often involving his extensive handgun collection, and heavy drinking.

An affair with the lead singer of the Ronettes, Veronica Bennett, known as Ronnie, led to the breakup of his marriage. His turbulent marriage to Ms. Bennett, chronicled in her 1990 memoir “Be My Baby,” ended in divorce.

“I loved him madly, and gave my heart and soul to him,” she said in a Facebook post on Sunday. “Unfortunately Phil was not able to live and function outside of the recording studio. Darkness set in, many lives were damaged.”

From time to time Mr. Spector showed the magic touch. In 1969, working for A&M records, he coaxed a hit out of Sonny Charles and the Checkmates, an obscure Las Vegas lounge act, with “Black Pearl,” a socially conscious song in praise of Black women.

The breakup of the Beatles in 1970 gave him a brief second life. Allen Klein, their manager, asked him to deal with the unfinished recordings the group had made at Apple’s studios in London the previous January. The resulting album, “Let It Be,” led to a series of collaborations with Mr. Lennon and George Harrison.

For Mr. Lennon, he produced “Imagine” and, in part, “John Lennon/Plastic Ono Band” and “Rock ’n’ Roll.” He worked with Mr. Harrison on the album “All Things Must Pass” and “The Concert for Bangladesh,” a live triple album of the two charity concerts at Madison Square Garden in New York organized by Mr. Harrison in 1971 to aid refugees from the Bangladesh-Pakistan war.

“Let It Be” received mixed reviews and was thoroughly repudiated by Paul McCartney, who hated the lush choirs and heavy orchestration, especially on “The Long and Winding Road.” At his instigation, Apple Records produced a de-Spectorized version of the record, released in 2003 as “Let It Be . . . Naked.”

In the late 1970s, in recording sessions marked by more than the usual chaos, Mr. Spector produced the Ramones’ album “End of the Century” and Leonard Cohen’s “Death of a Ladies’ Man.” Neither album was successful.

Mr. Spector was inducted into the Rock & Roll Hall of Fame in 1989. A boxed set of his recordings from 1958 to 1969, “Phil Spector: Back to Mono,” was released by Phil Spector Records in 1991.

In addition to his daughter Nicole, survivors include his partner, Janis Zavala.

In the early hours of Feb. 3, 2003, Mr. Spector, after drinking heavily, drove to his home in Alhambra, Calif., with Lana Clarkson, a struggling actress he had just met at the House of Blues, where she worked as a hostess. His chauffeur, waiting behind the house, later testified that he heard a popping sound, after which Mr. Spector emerged, a revolver in his hand, and said, “I think I killed somebody.”

Mr. Spector was charged with second-degree murder. His defense argued that Ms. Clarkson, depressed about her failed acting career, had committed suicide.

A first trial, in 2007, ended in a hung jury. Mr. Spector was retried in 2009 and found guilty. He received a sentence of 19 years to life, which he was serving at the California Health Care Facility in Stockton. Because of his declining health, he had been moved from the California State Prison in Corcoran in 2014.

Marie Fazio and Lauren Wolfe contributed reporting.