ment, and he won people over wherever we played, from every culture and every corner of the world.  Redferns via Getty Images

Fans and fellow musicians rallied around the singer throughout his illness, helping raise money for his medical expenses through benefit concerts and fundraisers.

In the band's tribute, Sick of It All thanked supporters for standing by Koller during his final years.

Want more celebrity and pop culture news? Start your day with Page Six Daily. Thanks for signing up! Enter your email address Please provide a valid email. By clicking above you agree to the Terms of Use and Privacy Policy. Want celebrity news as it breaks? Check out more newsletters

 You all helped Lou feel very special and very loved as he battled away these last two years,  the band wrote.  His battle is over now and he can finally rest. Hopefully he can somehow still see and feel the beautiful, positive mark he left on the world. 

Tributes quickly poured in on Instagram, including from WWE star CM Punk, who wrote,  Love you Lou and SOIA. Thank you for the soundtrack for my life. Sending hugs. 

6 Koller first revealed in June 2024 that doctors discovered a cancerous tumor in his esophagus that spread into his stomach. Redferns via Getty Images

6 After months of chemotherapy, the rocker shared in May 2025 that he was cancer-free. However, just a few months later, he revealed the cancer had returned. Redferns

Singer-songwriter Chuck Ragan also wrote,  Lou was indeed a pillar in our world of music to me and will never be forgotten,  while Pennywise guitarist Fletcher Dragge added,  No words, a true gentleman and a pioneer, when I think of Hardcore, Lou is the first name that pops into my mind, thank god we had the privilege to enjoy the stage with him and the boys many time over the years, he was always a unforgettable presence on the stage, and one of the best hangs off the stage as well. 

Meanwhile, Pennywise's lead singer Jim Lindberg wrote,  The best to do it, and a real good human. Devastated for your loss, for the family, for all of us. I can remember playing shows with you guys and hearing the strength in his voice and thinking,  How am I supposed to follow that?!!  Many Bro Hymns will go out to Lou now. Rest easy brother and love to all. 

Born and raised in Queens, New York, Koller co-founded Sick of It All in 1986 alongside his brother Pete Koller and drummer Armand Majidi. Over the next four decades, the band became one of the defining acts of the New York hardcore scene, releasing 12 studio albums and earning a devoted international following.