Martin Eric Ain of Celtic Frost passed away on Saturday (10/21) after suffering a heart attack at age 50. His close friend Jan Graber confirmed the news to Swiss website 20 Minuten.

Martin was an on-and-off member of Celtic Frost throughout various phases of their career, and played bass and sang on most of their albums. He also played in pre-Celtic Frost band Hellhammer with band leader Thomas Gabriel Fischer, aka Tom G. Warrior. Tom took the above photo back in 2006 and posted it to Twitter after the news of Martin's death. Tom also wrote on Facebook: "I am deeply affected by his passing. Our relationship was very complex and definitely not free of conflicts, but Martin's life and mine were very closely intertwined, since we first met in 1982." He also posted a stream of "Totengott," and wrote: "...lyrics and lead vocals by Martin Eric Ain, music by Tom Gabriel Warrior, recorded in December of 2005. This was the final musical collaboration between Martin and me, and it now will remain so forever."

Several other artists posted tributes on social media, including Misanthrope, Samael, Lord Dying, Cradle of Filth, 1349, With the Dead, Satyricon, Goatwhore, Xibalba, Child Bite and Pictureplane. See those tributes below.

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