John Carl Hartmann

John Carl Hartmann, age 84, of Oconomowoc, Wisconsin, fondly known as “Uncle Jack” peacefully passed away on October 15, 2025. He was born on June 2, 1941, in Phillips, Wisconsin, to Carl and Rose Hartmann.

An esteemed member of the Marine Corps and one of the founding fathers of the Trogs Motorcycle Club, John enjoyed the camaraderie of his fellow members and shared many adventures with them. He was an avid outdoorsman, finding joy in deer hunting on his land and spending time on the waters of Lac La Belle and Fowler Lake. His love for outdoor activities also extended to skiing—both on snow and water—and he cherished the moments spent scuba diving, where he served as an instructor and dive master.

John was a longtime attendee of St. Catherine Church, where he participated in parish life for over twenty years. With a fondness for the Old West, he enjoyed watching programs on Grit and often spent his evenings with those he loved, including his beloved Labrador retrievers.

John’s legacy continues through his son, Chris (Andrea) Hartmann. John is further survived by his grandchildren Kalya Hartmann, Johnny (Jasmine) Hartmann, Cheyanne Hartmann, Paige Hartmann, and Camden Hartmann; his great-grandchild John Christopher Hartmann; his brother Roger Hartmann and sister Diane (Tom) Curaski; and nephews Robert Hartmann and Tom Hartmann.

John’s family would like to express their heartfelt gratitude to the staff of Alden Estates in Jefferson and Rainbow Hospice in Johnson Creek for their exceptional care and support during his final days.

In lieu of flowers, family asks donations to be designated to the Alzheimer’s Association in remembrance of John.

A memorial service for John will be held on Saturday, November 1, 2025. Visitation will take place from 3:00pm to 4:00pm at Pagenkopf Funeral Home (2228 N Silver Maple Ln, Oconomowoc, WI 53066) followed by a service at 4:00pm.