Seymour Stein, the man who helped launch the careers of Madonna, the Talking Heads and the Ramones, died Sunday at the age of 80.

According to a statement by his family, he died of cancer in Los Angeles.

Over the course of his star-studded career, Stein worked with prominent bands and recording artists like the Rolling Stones, Lou Reed, Depeche Mode, The Pretenders, The Smiths and The Cure.

Madonna took to Twitter to mourn his loss, as well as express her gratitude, describing Stein as "one of the most influential" men in her life.

Early start in music industry

Stein was born in Brooklyn, New York City, in 1942, and by age 13 was already a clerk at music magazine Billboard. He helped develop the Billboard Hot 100, launched in August 1958.

By his late teens, Stein was working summers at the Cincinnati-based King Records, James Brown's label, and by his mid-20s had co-founded Sire Productions (which later became Sire Records).

Stein was married briefly to record promoter Linda Adler, with whom he had two children: filmmaker Mandy Stein and Samantha Lee Jacobs, who died of brain cancer in 2013. Stein and Adler divorced in the 1970s, and Stein later came out as gay.

Stein's label Sire was acquired by Warner Bros in 1978 and over the next two decades, Warner signed acts such as The Replacements, Echo & the Bunnymen, Madness, The Undertones, The Smiths and lead singer Morrissey.

Brian Wilson, Seal, Ice-T, Lou Reed and Everything But the Girl also joined the stable.

Signing Madonna while in the hospital

In the early 1980s, Stein made what turned out to be the biggest discovery of his illustrious career after hearing a demo tape of a little-known artist from the New York club scene: Madonna.

"I liked Madonna's voice, I liked the feel, and I liked the name Madonna," he wrote in his 2018 memoir Siren Song. "I liked it all and played it again."

Stein was in the hospital with a heart infection around the time of his career-defining discovery. He was so excited to meet the soon-to-be-legend, however, that he had her brought to his hospital room.

"She was all dolled up in cheap punky gear, the kind of club kid who looked absurdly out of place in a cardiac ward," he wrote. "She wasn't even interested in hearing me explain how much I liked her demo. 'The thing to do now,' she said, 'is sign me to a record deal.'"

'He changed my world'

Many others who worked with Stein also posted tributes on social media, including Madonna.

"Seymour Stein Has Left Us! I need to catch my breath. He Was one of the most influential Men in my Life!! He changed and Shaped my world. I must Explain," she tweeted with a longer post on Instagram.

Johnny Marr, the guitarist and co-songwriter for The Smiths, tweeted: "Legendary record man. Signed me to Sire Records in 1984 and bought me my Red 355 from 48th Street to seal the deal. Worked with The Drifters, Rolling Stones & Shangri-Las. Discovered Talking Heads, Ramones & Madonna. Well done Seymour & thank you my friend."

American rap artist Ice-T posted: "It’s a Sad day for me and all of music. Love you Seymour."