Chris Squire, the co-founder and longtime bassist of prog rock icons Yes and the only member of the group to feature on every studio album, has passed away just over a month after revealing that he was suffering from a rare form of leukemia. Squire was 67. Current Yes keyboardist Geoff Downes first tweeted the news, “Utterly devastated beyond words to have to report the sad news of the passing of my dear friend, bandmate and inspiration Chris Squire.”

Yes formed in 1968 after singer Jon Anderson met self-taught bassist Squire at a London music-industry bar; the pair were soon joined by guitarist Peter Banks, keyboardist Tony Kaye, and drummer Bill Bruford. Yes released their self-titled debut in 1969. However, it wasn’t until Steve Howe and Rick Wakeman replaced Banks and Kaye, respectively, that the prog rock group really hit it big with 1971’s The Yes Album and Fragile. Over the ensuing decades, Yes would see a parade of band members depart, enter and reenter, but Squire was the lone constant in the shape-shifting band, serving as their bassist for nearly 50 years. Squire is also credited as a co-writer on many of Yes’ greatest cuts, including “I’ve Seen All Good People,” “Starship Trooper,” “Owner of a Lonely Heart,” “Yours Is No Disgrace” and “Heart of the Sunrise.”

In addition to his work with Yes, Squire was involved in other side and solo projects. His 1975 solo LP Fish Out of Water is revered among prog fans. Squire also teamed with Yes part-time guitarist Billy Sherwood for their Conspiracy project in 2000 and, more recently, formed Squackett with Genesis guitarist Steve Hackett. Yes’ current incarnation featured singer Jon Davison, and as Squire told Rolling Stone, the vocalist was hired based on a recommendation from Foo Fighters’ Taylor Hawkins. In May, Squire revealed that he was recently diagnosed with acute erythroid leukemia, which would force him to miss the band’s summer co-headlining tour with Toto. The absence marked the first time in the band’s history that Yes performed without their longtime bassist.

Squire’s children are Carmen, Chandrika, Camille, Cameron and Xilan. Squire met his first wife Nikki in 1970 at a club in London. They married in 1972. She sang on the 1981 Christmas single “Run with the Fox” and also the track “Hold Out Your Hand” from Fish Out of Water (1975). In 1983, she formed Esquire, on whose first album Chris, Alan White and Trevor Horn assisted. Their family included Carmen, Chandrika and Camille Squire. The couple divorced after fifteen years of marriage. Squire married actress Melissa Morgan on 8 May 1993. She played Brittany Norman on The Young and the Restless and later returned to the daytime programme as Agnes Sorensen. The pair divorced in 2004. His third and final marriage was to Scotland Squire, who gave birth to daughter Xilan in 2008. They resided in the Chelsea neighbourhood of London, and latterly in Phoenix, Arizona.