Legendary recording artist Tom Petty died at a Los Angeles hospital on Oct. 2, after being found unconscious at his Malibu home. (Erin Patrick O'Connor/The Washington Post)

Tom Petty, a singer and guitarist who burst onto the scene in the 1970s as one of the most original, searching voices in rock and remained a major hitmaker for four decades, writing songs that included “Free Fallin’,” “I Won’t Back Down” and “American Girl,” died Oct. 2 at a hospital in Santa Monica, Calif. He was 66.

Mr. Petty died in a hospital after being found unconscious at his home in Malibu, according to Tony Dimitriades, longtime manager of Petty and his band, the Heartbreakers. He had suffered cardiac arrest.

Tom Petty and the Heartbreakers released their self-titled debut in 1976 and soon drew comparisons to the bluesy, guitar-heavy rock of the Rolling Stones and the Byrds. Their music was unabashedly sentimental, seeming to speak to striving, everyday Americans no less than the songs of fellow rocker Bruce Springsteen, while featuring clever arrangements that intertwined the fretwork of Mr. Petty and lead guitarist Mike Campbell.

The group toured seemingly nonstop for decades, leading boisterous shows as recently as last week, when Mr. Petty concluded a nationwide tour that he said might be his last. “I don’t want to spend my life on the road,” he told Rolling Stone.

Still, Mr. Petty seemed to treat rock as a religion, battling with his record label to prevent the cost of one of his albums from rising by $1 and exuding a sense of divine satisfaction while performing onstage. “I don’t think he thought there was a better way to live your life than in a rock band,” said rock historian and Rolling Stone contributor Anthony DeCurtis. “You never get a sense that this guy was going through the motions at all. It was a matter of conviction for him.”

Musician Tom Petty performs at a benefit for Haiti in January 2016 in Beverly Hills, Calif. (Alberto E. Rodriguez/Getty Images)

Mr. Petty, the group’s leader and principal songwriter, was a musical craftsman who paired polished guitar riffs with lyrics that seemed lifted from barroom conversations in his home town of Gainesville, Fla. His 1978 single “Listen to Her Heart” begins, “You think you’re gonna take her away with your money and your cocaine,” while “I Won’t Back Down” — the 1989 fist-pumper that Mr. Petty co-wrote with Jeff Lynne — starts this way: “Well, I won’t back down / No, I won’t back down / You can stand me up at the gates of hell / But I won’t back down.”

It was simple, straightforward and catchy, with a hummable hook that helped Mr. Petty’s solo debut, “Full Moon Fever” (1989), sell millions of copies. Mr. Petty and the Heartbreakers’ “Greatest Hits” record, a compilation that included the harmonica-driven single “Mary Jane’s Last Dance,” fared even better, sitting on the top-200 albums chart for more than six years and briefly staking a claim to one of the 100 best-selling albums of all time.

Mr. Petty’s career was marked by personal problems that included heroin addiction, a tumultuous marriage and a 1987 house fire that burned everything but his basement recording studio. But he remained one of the most durable and distinctive presences in rock for decades, with his signature nasal voice and blond hair that fell to his shoulders.

His 1980s music videos, including an “Alice in Wonderland”-inspired video for “Don’t Come Around Here No More” (1985) in which Mr. Petty played a sunglasses-wearing Mad Hatter, introduced him to some members of the MTV generation. And his recordings with the Traveling Wilburys, a supergroup that formed in 1988 with Bob Dylan, George Harrison of the Beatles, Lynne of Electric Light Orchestra and Roy Orbison (who died later that year), connected him with an earlier era of rock music.

Still, Mr. Petty remained an inscrutable presence to many fans. As one friend told Petty biographer Warren Zanes, “He’s got tinted windows on his soul.”

Thomas Earl Petty was born in Gainesville on Oct. 20, 1950, the son of an alcoholic insurance salesman who beat him relentlessly from the time he was 5. His body, he later said, was covered in welts. His revenge was a slingshot to the fin of his father’s 1955 Cadillac.

He escaped the pain of his family life through watching television and listening to rock music. He became obsessed with the guitar, grew his hair long in the style of the Beatles, dropped out of school at 17 and devoted himself to playing in local rock bands.

One of the groups, Mudcrutch, featured two later-foundational members of the Heartbreakers — keyboardist Benmont Tench and lead guitarist Campbell. Mudcrutch signed with Shelter Records in Los Angeles, but the band soon broke up. Not until 1975, at a demo session that included Tench, Campbell, drummer Stan Lynch and bassist Ron Blair, did Mr. Petty suddenly find the chemistry just right.

Calling themselves Tom Petty and the Heartbreakers, they released two major hits the next year, “American Girl” and “Breakdown,” which vaulted them to national attention and a regular spot performing at the Whisky a Go Go and other major Los Angeles clubs.

Their style was a rejection of arena-rock bands such as Led Zeppelin and the blues roots music of the Allman Brothers in favor of the feral sound of early Elvis Presley and Buddy Holly.

Legal entanglements ensued when his record company changed hands after the release of the band’s second album, “You’re Gonna Get It!,” in 1978. Mr. Petty said he refused to be “bought and sold like a piece of meat,” and he found his career stalled over charges of breach of contract when he wanted out. He declared bankruptcy in 1979, signed with a new label, Backstreet Records, and reached a settlement with his former record company.

The new arrangement would mark a renaissance in Mr. Petty’s music. The record “Damn the Torpedoes” (1979) — a playful jab at his legal troubles — endures as one of the timeless rock albums of the era, oozing tenderness and toughness and a propulsive rock drive on songs such as “Refugee” and “Louisiana Rain.”

Mr. Petty’s next several albums with the Heartbreakers — including “Hard Promises” (1981), with a duet with Stevie Nicks of Fleetwood Mac on the song “Insider,” and “Long After Dark” (1982) — continued to sell exceedingly well. Critics rhapsodized on his originality and suppleness.

“Long After Dark,” New York Times music critic Robert Palmer wrote, was “one of the most gorgeous-sounding rock-and-roll albums in recent memory. Mr. Petty and his collaborators have fashioned an aural landscape of remarkable beauty and depth. Phalanxes of electric 12-stringed guitars advance across meadows of layered keyboards, while 6-strings chime out harmonious, pealing chords and drums crash like thunder.”

Worried that the Heartbreakers were becoming too well oiled for their own good, Mr. Petty ventured into conceptual rock — with touches of psychedelia and soul — for their 1985 album “Southern Accents,” which had the one-off hit “Don’t Come Around Here No More.”

In 1986, he and the Heartbreakers toured as the backing band for Dylan, one of Mr. Petty’s chief musical influences. Their next album, “Let Me Up (I’ve Had Enough)” in 1987, demonstrated a shaggy freewheeling spirit more than their previous polished studio work and a virtuoso-like versatility, but Mr. Petty also saw his commercial prospects dwindling.

His work with the Traveling Wilburys, and the chart-topping success of “Free Fallin’ ” and “I Won’t Back Down” from “Full Moon Fever,” propelled him into the next decade. As Mr. Petty put it, the album “made me such a nice guy for about a year.” He was now a household name, an arena-filling act who suddenly became a target for music critics anticipating that he — now on the precipice of fame — would relinquish his mantle as an innovator and leave behind his roots in favor of lucre.

His later albums, among them “Into the Great Wide Open” with the Heartbreakers and the solo “Wildflowers,” continued to reap financial rewards for its creator, but he remained very much attuned to musical integrity. His music lacked superstar pretensions in favor of exquisite melodies and high-level craftsmanship. He tried to avoid the pitfalls of 1980s rock-band excess, and he embraced the hallmarks of the post-Nirvana generation of music­makers.

“They don’t give a damn how much money they’re going to make,” he told the London Independent in 1994. “I think in America for a long time you had groups that wanted to be stars more than they wanted to make music. We always went on the theory that if we made really good music we might attain stardom, but it was never the primary goal.”

Mr. Petty made idiosyncratic guest appearances in the 1997 Kevin Costner film “The Postman” and on TV shows that included “It’s Garry Shandling’s Show” and the animated series “King of the Hill.”

His marriage to Jane Benyo, with whom he had two daughters, ended in divorce; he said her escalating drug use and mental illness, including threats of suicide, exacerbated his own prodigious heroin consumption and a furtive public posture. In 2001, he married Dana York in a ceremony presided over by rock star and ordained minister Little Richard. A complete list of survivors could not be immediately confirmed.

The Rock and Roll Hall of Fame inducted Mr. Petty and the Heartbreakers in 2002. “I’d like to see us break some new ground and leave some sort of mark on the music,” Mr. Petty once said, according to his citation. “That would be the nicest thing — to give something back, as noble as it sounds. If you could make some little dent in rock, where that little area is yours — that’s what I’m striving for now.”