Greg Lake, a singer and multi-instrumentalist who helped propel prog rock into the mainstream as a member of Emerson, Lake and Palmer and King Crimson, died Tuesday. His manager told the BBC he had recently had “a long and stubborn battle with cancer”; the news comes nine months after the death of his bandmate, Keith Emerson. He was 69. As a lyricist and vocalist, Lake helped define prog rock’s flair for introspection with a dash of fantasy. He sang with clarity and confidence, making his voice a singular force among his and his fellow musicians’ experimentation. Whether playing bass or guitar, as he often did with Emerson, Lake and Palmer, he wrote in a way that allowed for his bandmates to build vast, intricate soundscapes. He was a skillful player whose guitar playing, in particular, added depth to some of ELP’s grand classical experiments, such as their rock interpretation of Russian composer Modest Mussorgsky’s Pictures at an Exhibition.

Greg Lake was born in Bournemouth, England on November 10th, 1947. He befriended eventual King Crimson leader Robert Fripp, who played guitar and lived nearby, and sought out opportunities to play music. In 1967, he joined the Gods, a group that had previously featured Rolling Stones guitarist Mick Taylor, but Lake left before they recorded their debut LP. The seeds of King Crimson were also formed in 1967 and Lake joined in 1968. The group played its first concert the following April and Lake sang lead vocals and played bass on their debut, 1969’s groundbreaking In the Court of the Crimson King – which Pete Townshend called “an uncanny masterpiece,” according to The Guardian – and its follow-up, 1970’s In the Wake of Poseidon. While on tour with King Crimson, Lake befriended Emerson, then a keyboardist of their tourmates the Nice. The two musicians had similar musical aesthetics and formed a new group, recruiting Palmer, who had played with the Crazy World of Arthur Brown and Atomic Rooster, to join them. The trio considered bringing a full-time guitarist into the fold – Lake was pulling double duty on bass and guitar – but, according to the book Legends of Rock Guitar, the only musician they all agreed could keep up with them was Jimi Hendrix and their acrynomic name would then become “HELP.”

Emerson, Lake and Palmer made their live debut in 1970, releasing their self-titled debut that same year. They were an near-instant hit. Each of the albums they put out in the Seventies – including their landmark Brain Salad Surgery – went gold in the U.S., and several charted in the Top 10 of Billboard’s album chart. The ambitious Tarkus, their second album – a deft and grandiose fusion of classical and rock – was a Number One album in the U.K. in 1971. Lake served as sole producer for most of the group’s works, which sold more than 48 million albums, according to the BBC. Their live performances featured light shows and theatrics, including the parading of their “Tarkus” mascot, and their highest-charting album in the U.S. was the live outing, Welcome Back, My Friends, to the Show That Never Ends – Ladies and Gentlemen, Emerson, Lake and Palmer. The group recorded the album in Anaheim, California in 1974; its title referencing lyrics in the Brain Salad Surgery track “Karn Evil 9.”

At the peak of ELP’s success in 1975, Lake put out a solo single, “I Believe in Father Christmas,” which was a Number Two hit in the U.K. behind “Bohemian Rhapsody.” After the trio disbanded in 1979, Lake launched a solo career and, in 1981, issued a star-studded self-titled LP, which featured performances by guitarists Gary Moore and Steve Lukather, drummer Jeff Porcaro and saxophonist Clarence Clemons. It made it up to Number 63 on the U.S. chart and its follow-up, 1983’s Manoeuvers, which also featured Moore, did not make the Top 200. Subsequently, Emerson and Lake regrouped in the mid-Eighties, but with drummer Cozy Powell instead of Palmer, who was playing with Asia. Their sole LP, Emerson, Lake and Powell, was a hit, making it up to Number 23 in the U.S. Palmer came back, and the original trio continued through much of the Nineties, with a reunion in 2010. He released a final solo album, Ride the Tiger, in 2015. In 2001, Lake toured as a member of the seventh incarnation of Ringo Starr & His All-Starr Band. In 2003, Lake played the bass on The Who song “Real Good Looking Boy”. The group’s usual bassist, Pino Palladino, was set to do it but he was touring during the time of recording, so Lake was asked instead.

In 2005, Lake toured Germany and the UK with his assembled group, the Greg Lake Band, which included David Arch on keyboards, Florian Opahle on guitar, Trevor Barry on bass, and Brett Morgan on drums. In 2006, Lake played as a member of the supergroup The RD Crusaders in aid for charity. Lake performed “Karn Evil 9” with the Trans-Siberian Orchestra at several shows. In 2010, Lake and Emerson completed an acoustic world tour, performing ELP songs. The tour got off at a bad start following a backstage altercation between the two, but “we completed the tour and it was very happy. We actually ended up enjoying ourselves”. In July 2010, Lake joined Emerson and Palmer for a one-off gig from Emerson, Lake & Palmer at the High Voltage Festival in Victoria Park, London, to commemorate the band’s fortieth anniversary. Lake continued to tour solo in the 2010s. His Songs of a Lifetime Tour began in 2012 which featured songs of his career and those by his favourite artists, including Elvis Presley and Johnny Kidd & the Pirates. The tour ended in November of that year.