Lou Koller, the longtime frontman and co-founder of the influential New York hardcore band Sick of It All, has died at the age of 59. His death, following a battle with esophageal cancer, was announced Friday by his bandmates.

"It's with unbelievable sadness that we announce to our worldwide hardcore family the passing of our brother Lou Koller. The level of loss that we feel at this time is overwhelming," the band wrote in a statement on Instagram. They described Koller as a "beloved friend and an iconic frontman," noting his unwavering commitment and enthusiasm throughout the band's nearly 40-year history.

Koller revealed in June 2024 that he had been diagnosed with a cancerous tumor in his esophagus that had spread to his stomach. This led to the cancellation of a European tour as he began treatment. Fans and fellow musicians supported Koller, organizing a benefit concert at Irving Plaza in Manhattan later that year to help with his medical expenses. In May 2025, Koller shared that he had completed his final chemotherapy round and was cancer-free, but the cancer later returned.

The band expressed gratitude for the support Koller received during his illness. "You all helped Lou feel very special and very loved as he battled away these last two years. 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," the statement read.

Born and raised in Queens, Koller, alongside his brothers Pete and Armand Majidi, formed Sick of It All in 1986. Koller credited his upbringing in Queens for shaping his perspective, telling Anti-Matter in 2024, "That's the way we were raised in our neighborhood in Queens. You didn't go out looking for trouble."

The band emerged as a defining act in the New York hardcore scene, releasing their debut album "Blood, Sweat and No Tears" in 1989. Sick of It All went on to release 12 studio albums, building an international following through decades of extensive touring.

Musicians across genres paid tribute to Koller. WWE superstar CM Punk, whose entrance motto is inspired by the band's 1995 song "Clobberin' Time," wrote, "Love you Lou and SOIA. Thank you for the soundtrack for my life. Sending hugs. Tonight's 'clobberin' time' is for Lou."

The Dropkick Murphys posted, "All our love to the SOIA family and especially the Koller family. Rest In Peace Lou we are so glad to have shared many great memories with you. Always a class act and gentleman. Gone but NEVER FORGOTTEN." Rancid's Lars Frederiksen also shared, "RIP to the legend."