William R Kostoff Obituary
It is with great sadness that we announce the death of William R Kostoff of Port Huron, Michigan, born in Ann Arbor, Michigan, who passed away on March 20, 2026, leaving to mourn family and friends. Leave a sympathy message to the family on the memorial page of William R Kostoff to pay them a last tribute.
He was predeceased by: his parents, Barbara Jane and Harold Richard Kostoff. He is survived by: his children, Corey Reed Kostoff and Jessica Rose Kostoff; his son-in-law Kenneth Lawrence Rusterholz; his grandchildren, Aurora McAllister Rusterholz and Blaze Caleb Rusterholz; his brother James Gregg Kostoff; and his former wife Marianne McAllister.
In lieu of flowers, please send donations to The Amyloidosis Foundation https://amyloidosis.org.
