Donald F. Barthelmess, Sr. passed away peacefully with family members by his side in Winter Park Florida on September 5th 2025. He was 89. Born in New York City in 1936, he was a longtime resident of Patchogue, Long Island, NY until retiring to Florida in 1996. He leaves behind a legacy of family, friends, gregarious humor and unsurpassed work ethic. He is survived by his beloved wife of 68 years Doris (Davis) Barthelmess and daughter Susan May (Tom) of Port St. Lucie, FL and son Don Barthelmess Jr. (Carol) of Santa Barbara, CA. His grandchildren include: Lindsay Gracey (David), Brian May (Gabriella), Rob Barthelmess (Nikki) and DeeDee Conrad (Kevin). His precious great-grandchildren are Oliver, Hadley, Liam, Robby, Jackson, Hollis and Brooke. He is also survived by his brother Richard Barthelmess and sister Anne-Marie Davis. He is predeceased by his parents John and Helen as well as brothers John, Edward, Leo and sister Helen Mary. "Cookie", as he was known by friends and family alike, was a passionate and generous man to all. He willingly shared his time, knowledge and expertise as a talented and skilled craftsman. It was widely known by all that he could do just about anything in the trades, and tackled all projects with precision and vigor. A fifty-year journeyman steamfitter of New York Local 638, Cookie was from a long family line of union steamfitters. He followed his father, grandfather and brothers in that trade. A mentor to many and always willing to help others, his mantra was: "Do it right, or don't do it at all." Always the life of the party, Cookie's sense of humor was unmatched, as he could recall and tell jokes for hours. The most important thing to him was his wife and the huge family that he came from and helped create. A Navy Reservist and an avid boater, he was a longtime member and served as Commodore of the Suffolk Boat Club in Patchogue, Long Island in 1972. In addition he was a member in the Patchogue Yacht Club and Patchogue Bay Power Squadron. He organized and enjoyed numerous family/friend boating voyages locally, on the Great South Bay, all over Eastern Long Island and up the lower New England coast. Settling in Cape Coral, FL after retirement he and his wife enjoyed leisurely cruises in the canals and trips to Sanibel & Captiva islands with family & friends. He was a true gentleman, brother, friend, husband, father, uncle, grandfather and great grandfather. He will be sorely missed, but never forgotten. His legacy shall live on through all that knew him. A Celebration of Life will be planned in the future at The Mayflower Retirement Community, Winter Park, Florida. Donations may be made in his memory to St Jude's Children's Hospital or the Alzheimer's Association.