William August Koloseike Obituary

With profound sadness, we say goodbye to William August Koloseike of Naperville, Illinois, born in Chicago, Illinois, whose vibrant spirit touched the lives of many. William left this world on November 6, 2025 at the age of 67, leaving a void in the lives of so many people. You can send your sympathy in the guestbook provided and share it with the family.

Though William has departed this earthly realm, his legacy endures — a legacy of love that will continue to illuminate the lives of family and friends in the darkest of hours. May his spirit soar on wings of eternal peace, forever cherished in the tender embrace of memory.

He is survived by: his wife Jan; his sons, Billy Koloseike and Blake Michaels (Max); his granddaughters, Kennedy and Remington; and his siblings, Mark Koloseike (Jean), Nina Koloseike and Judy Spellman (John). He is also survived by several nieces and nephews.

In lieu of flowers, please make a donation in memory of William A. Koloseike to support lung cancer research under the direction of Dr. Marina Garassino at the University of Chicago Medicine.