Gary Diffenderfer of O’Fallon, Missouri, passed away on October 15, 2025, at the age of 73. He was born on January 24, 1952, in St. Louis, Missouri, the son of Carl and Gladys (Wood) Diffenderfer.

Gary was an avid fisherman who found great joy in spending time outdoors, especially at Brommelsiek Park where he loved to cast a line and enjoy the peaceful surroundings. A fan of fast cars and classic American sports, Gary was a devoted NASCAR enthusiast and enjoyed watching baseball and football on television.

He is survived by his loving mother, Gladys (Wood) Diffenderfer; his beloved son, Lt. Col. Jeff Diffenderfer, M.D., of Cataula, Georgia; his cherished grandchild Matthew and his loving siblings: Mark (Teresa) Diffenderfer of Hawk Point, Missouri; Renee (Ron) Randell of St. Peters, Missouri; and Corliss (Dave) Pogue of Saint Peters, Missouri.

Gary is also fondly remembered by his nieces and nephews: Daniel Diffenderfer, Samantha (Kenny) Forbes, Jason (Carolyn) Randell, Autumn (Chris Allgood) Randell, Mariah Randell, Amber (Joe) Vorce, and Rachel (Chase) Jones.

He was preceded in death by his father, Carl Diffenderfer.

Gary will be deeply missed by his family and all who knew and loved him.

Memorial donations may be made to: Mid-America Transplant Foundation, (midamericatransplant.org/get-involved/make-a-contribution/), 1110 Highlands Plaza Dr. East, Suite #100, St. Louis, MO 63110