Legendary musician and cultural icon David Bowie died Sunday after an 18-month battle with cancer, his family has announced. The singer’s illness was not publicly announced until his passing. His death comes just two days after his 69th birthday and the release of his latest album, Blackstar, which is rightly being considered his best work in years.

Bowie was born David Robert Jones in 1947, beginning his music career in the ’60s and quickly rising to fame in the early ’70s with hits like “Space Oddity,” “Changes,” “Ziggy Stardust” and “Life on Mars.” In the ensuing years and decades, Bowie refused to be tethered to any set definition of his persona and style, reinventing himself countless times–as Major Tom, Ziggy Stardust, The Thin White Duke, but above all, a Hero to the outsider and an inspiration to nearly every popular musician who has come of age after his rise to fame. 

Since the unexpected news of his death broke, the outpouring online and on social media has been constant, with everyone in the music world offering condolences and tributes.  Iggy Pop writes on Twitter: “David’s friendship was the light of my life. I never met such a brilliant person. He was the best there is.” Madonna, who’s own constant reinvention of herself was inspired by Bowie, says “this artist changed my life,” citing her first concert experience in Detroit.  

Maybe the most poignant tribute comes in a post by Tony Visconti, longtime friend and producer of Bowie music. The two first worked together on Bowie’s second album, 1969’s Space Oddity (originally David Bowie). Visconti also worked with Bowie on his more recent work, including his final release, Blackstar. The producer offers a short summation of an indescribable genius, calling his post-album death “a work of Art”:

He always did what he wanted to do. And he wanted to do it his way and he wanted to do it the best way. His death was no different from his life – a work of Art. He made Blackstar for us, his parting gift. I knew for a year this was the way it would be. I wasn’t, however, prepared for it. He was an extraordinary man, full of love and life. He will always be with us. For now, it is appropriate to cry.