Karl Wallinger, the multi-instrumentalist and solo force behind the band World Party and former member of The Waterboys, has died.

Wallinger, 66, passed away Sunday, his publicist said. No cause of death was announced.

Wallinger had worked as musical director for a production of "The Rocky Horror Show" in London’s West End when he was recruited on keyboards for The Waterboys in 1983, playing synthesizer and singing backup vocals on their most commercially successful song, "The Whole of the Moon."

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Waterboys founder Mike Scott called him "one of the finest musicians I’ve ever known" in a post Monday on X, formerly Twitter. "Travel on well my old friend," he said.

Creative differences with Scott led Wallinger to go his own way in 1985 to start World Party, where he created a sound infused with influences of the Beatles, Bob Dylan, Van Morrison and Sly Stone.

"It just became obvious that it wasn’t going to go anywhere than where it’s gone," Wallinger told Penny Black Music in 2022 interview. "(Mike Scott) was controlling, and that was it, he wasn’t into doing anything together."

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World Party was better received critically than commercially and despite landing several tunes on the pop music charts, it was more embraced by alternative radio.

"Ship of Fools" reached No. 5 on Billboard’s mainstream rock chart in the U.S. in 1987. "Way Down Now," went to No. 1 on the Billboard alternative chart in the U.S. in 1990. "Is it Like Today" was his biggest hit in the U.K., reaching No. 19 in 1993. Wallinger's song "She’s the One" became a No. 1 single for Robbie Williams in 1999.

Wallinger worked on Sinéad O’Connor’s debut album, The Lion and the Cobra, and she lent her vocals to his second album, "Goodbye Jumbo," which was nominated for a Grammy for best alternative music performance. Q Magazine named Jumbo is 1990 album of the year.

Wallinger was one of many artists who recorded with Peter Gabriel for his Big Blue Ball album.

Gabriel said on X that he was shocked and saddened to learn of the death. He said he admired Wallinger’s work from afar but reached a new level of appreciation when they worked together on what he said was the most creative and fun week he ever had in the studio.

"Karl was overflowing with wonderful musical ideas that blew us all away, all delivered with terrible jokes that had us laughing uncontrollably all day and night," Gabriel said. "He was such a gifted, natural writer and player, it was a tap that he could turn on at will, effortlessly."

Mike Andrews of Enable Music, an artist management company in the U.K., who worked with Wallinger on a couple albums, called him a "genius who was never appreciated as widely as (he) should have been."

Wallinger served as musical director for the 1994 Ben Stiller-directed film "Reality Bites," starring Ethan Hawke and Winona Ryder.

Wallinger grew up in Prestatyn, Wales, where as a teen he played in PAX, a punk band with Nigel Twist and Dave Sharp, who would go on to form The Alarm. Twist recalled on Instagram that they would hammer out tunes in the loft of Wallinger's home.

Twist called him "an extraordinary talent, gifted singer/songwriter and multi-talented musician and producer."

"His songs never fail to reach deep inside and touch your soul," Twist said. "No matter how you feel, his music would fill you with joy and hope and above all, love, for a better world."

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In 2001, Wallinger had a brain aneurysm and spent years learning how to speak again and play instruments. He returned to touring five years later but never released any more albums.

During his Penny Black Music interview, Wallinger said William's hit cover of "She's the One" had rescued him financially after his health setback.

"It was lucky for me that he did it, because he kept us all in biscuits," Wallinger said. "Everything would have changed; I’d have had to have sold the kids. Got rid of the house and dismantle everything."

Wallinger is survived by his wife Suzie Zamit, son Louis Wallinger, daughter Nancy Zamit and two grandchildren.