John Anthony Kosidowski, 95, of Mercer, passed away on Wednesday, October 14, 2026, at Careview Nursing Home in Minocqua.

John was born on January 17, 1931, in Milwaukee to Edward and Verna (Wutkowski) Kosidowski. He proudly served in the U.S. Navy during the Korean War with the Seabees, attaining the rank of Chief Petty Officer before receiving his honorable discharge.

John retired from General Motors after 40 years of service as a senior designer. Throughout his career, he worked on groundbreaking projects, including the first guidance system and the Apollo program and lunar excursion module, contributing to the project from its beginning through the historic moon landing in July 1969. In addition to his career with General Motors, John and his family operated a grocery store in Tichigan, Wisconsin.

John was united in marriage to Audrey A. Konieczny on September 26, 1953, at St. Agnes Catholic Church in Milwaukee. Together, they raised five children before Audrey’s passing in 1989. On August 24, 1996, John married Francoise “Fran” Bouffard at the Community Church in Manitowish Waters.

An avid outdoorsman, John enjoyed fishing and chartering sport fishing trips on the Great Lakes. He also represented and guided for Quebec outfitters, leading caribou, fishing, and bear-hunting excursions. Hunting, fishing, and spending time outdoors with his family were among his greatest joys. He was also a devoted Green Bay Packers fan.

John is survived by his wife, Fran; three sons, Daniel, James (Kim), and John (Sue Anne) Kosidowski, all of Mercer; two daughters, Debra (David Lange) Morgan of Ludington, Michigan, and Sandy (Don) Pett of Shanty Town, Wisconsin; five grandchildren, Julie (Matt), Nicholas (Courtney), Lisa (Jon), Michael (Brittany), and Ashley; and 14 great-grandchildren, Emily, Rachel, Riley, Evan, Cael, Mason, Mariah, Brailynn, Bentley, Jax, Makayla, Addisyn, Karsyn, and Bryant. He is also survived by his sister, Janet (Thomas) Jashinsky; sister-in-law, Mary Ann Kosidowski; brothers- and sisters-in-law; nieces; nephews; and other relatives and friends.

John was preceded in death by his parents; his first wife, Audrey; brothers, Edward, Thomas, Robert, and Charles; and sisters, Lillian Brent and Mildred Blichavz.

Visitation for John will be held on Monday, October 19th from 10 a.m. until the Mass of Christian Burial at 11 a.m. with Fr. Maria Joseph Kodiganti officiating held at St. Isaac Jogues Catholic Church in Mercer. Burial will take place at Mercer Cemetery, with a luncheon following at church. A celebration of John’s life will be held in the future.