Steve Harwell, Voice of the Band Smash Mouth, Is Dead at 56

Steve Harwell, the former lead singer of the rock band Smash Mouth, which was best known for its 1999 hit “All Star,” died on Monday. He was 56.

His death, at his home in Boise, Idaho, was confirmed by the band’s manager, Robert Hayes, who said the cause was liver failure.

Smash Mouth was founded in 1994 in San Jose, Calif., and was made up of Mr. Harwell, the guitarist Greg Camp, the drummer Kevin Coleman and the bassist Paul De Lisle. Its first success came with the song “Walkin’ on the Sun,” from the band’s debut album, “Fush Yu Mang” (1997).

An upbeat track with a dark undertow, calling to mind both the Doors and contemporary ska-punk, “Walkin’ on the Sun,” with songwriting credits going to all four band members, went into steady rotation on MTV and topped Billboard’s alternative chart.

The song’s music video laid out the band’s aesthetic and attitude. Dressed in short-sleeve shirts and shades, with fedoras and soul patches, the four members looked like rougher versions of the image-obsessed retro hipsters depicted in the 1996 comedy “Swingers.” The video features a dance party straight out of a 1960s beach movie and ends with a drag-race crash, with Mr. Harwell — beefy, with tattoos on his arms — behind the wheel.

“The question of a particular style never once crossed our minds,” Mr. Harwell said in a 1997 interview. “We didn’t want to be labeled as a punk band, a ska band, a surf band, a rock band, a pop band or a whatever band. We just wanted to be us, Smash Mouth, and leave it to the people to interpret what we are.”

The band’s big-time crossover came with “All Star,” from its next album, “Astro Lounge,” in 1999. Backed by harder-driving guitars, Mr. Harwell, with a slight sneer, sings an outsiders’ anthem to ignore ridicule and shoot for the moon:

“All Star” — written by Mr. Camp, the band’s guitarist — went to No. 4 on Billboard’s Hot 100 singles chart, the band’s best-ever chart position, and found a lasting audience through movie soundtracks. In 1999, it was used in “Inspector Gadget” and “Mystery Men,” and two years later the song got its broadest exposure when it played during the opening credits of “Shrek,” the animated hit that featured Mike Myers as a grouchy but good-hearted ogre.

The “Shrek” soundtrack — which also featured Smash Mouth’s amped-up version of the Monkees’ “I’m a Believer,” in the closing scene — went double platinum, and the film won an Academy Award for best animated feature. “All Star” was everywhere.

“We had no clue how big ‘Shrek’ was going to be,” Mr. Harwell recalled in a 2019 article in Rolling Stone. “We sold millions of records off that alone. The song was reborn again.”

Since then, “All Star” has lived on, becoming a rich source for online parodies. Nearly 25 years later, the song has garnered nearly a billion streams on Spotify alone, and the sound of Mr. Harwell’s slightly raspy voice is still linked to the song’s recognizable opening lines: “Somebody once told me/The world is gonna roll me/I ain’t the sharpest tool in the shed.”

Steven Scott Harwell was born on Jan. 9, 1967, and grew up in San Jose. He began his musical career as a rapper with the group F.O.S., which stood for Freedom of Speech. With a sound reminiscent of West Coast groups of the late 1980s and early ’90s like N.W.A and Cypress Hill, it released a single, “Big Black Boots,” in 1993. But by then Mr. Harwell was already restless.

“Around the time we were about to put out our single, this kid Snoop Dogg came out and changed everything,” he recalled in 2017 interview with the music website Stereogum. “I was at a radio convention in Las Vegas watching MC Hammer, of all people, and I just looked at my manager, ‘I’m tired of all this hip-hop’” — he added an expletive — “‘I want to start an alternative rock band.’”

After “Astro Lounge,” Smash Mouth released five more studio albums through 2012, with diminishing levels of success. In 2006, Mr. Harwell was a cast member on “The Surreal Life,” a reality show on VH1 in which onetime celebrities live together; his fellow cast members included Sherman Hemsley of “The Jeffersons,” Florence Henderson of “The Brady Bunch” and Tawny Kitaen, known for her appearances in Whitesnake music videos.

For the last decade, Mr. Harwell’s career had been marked by health problems and occasionally erratic behavior. In 2013, he was diagnosed with cardiomyopathy, a heart condition, and Wernicke’s encephalopathy, a neurological condition that can affect speech and memory.

In August 2020, while many parts of the country were still under major restrictions related to the Covid-19 pandemic, Smash Mouth appeared at the Sturgis Motorcycle Rally, a huge annual event in South Dakota, and performed before thousands of fans — very few of whom, according to reports and videos of the event, were wearing masks or taking any precautions.

Mr. Harwell drew cheers from the crowd — but wide condemnation elsewhere — when he said from the stage, “We’re all here together tonight, and we’re being human once again,” and made a crude dismissal of the viral threat.

In 2021, Mr. Harwell left the band and retired from performing after a live show in upstate New York during which he was seen slurring his words, using profanity and apparently giving a Nazi salute.

“I’ve tried so hard to power through my physical and mental health issues, and to play in front of you one last time, but I just wasn’t able to,” he said in a statement at the time.

He is survived by his fiancée, Annette Jones; a brother, Mark; and three sisters, Carla Crocker, Michelle Baroni and Julie Harwell.

In 2022, Smash Mouth recruited a new lead singer, Zach Goode, and the group has concerts scheduled in coming weeks, including one on Thursday in Madera, Calif. Mr. Hayes, the manager, said the band was still scheduled to perform there.

In a statement on Monday, Mr. Goode said: “I love singing these songs every night and carrying on the spirit of rock n roll in front of the best fans in the world. I will continue to try, in my own way, to honor what Steve and the band have created.”