Donald Lawrence Cassidy died peacefully on November 8, 2021, at Brentwood at Fore Ranch. Don was born May 26, 1933 in Greenwich, Connecticut, the third son of the late John D. and Ursula Cassidy (née Lynch).  Don's life experiences ranged from his MIT education in engineering to service in the United States Army and, eventually, as Vice President of Hughes Aircraft in Los Angeles, California.  After retiring from Hughes, Don moved from Los Angeles to Santa Fe, New Mexico and then to Ocala, Florida, where he enjoyed and shared the last 18 years with friends and nearby family.  Don is preceded in death by his partner, John Zawadzki, his brothers, J. Robert and Richard, and his sister-in-law, Sara Cassidy, (née McNelis) and two nephews.  He is survived by his cousins Carol Miller and Scott Sedita, his sister-in-law, June Cassidy (née Consley), his beloved dog, Daisy Mae, numerous nephews, nieces and countless friends. A Funeral Mass will be held at Queen of Peace Catholic Church, 6455 S.W. State Road 200, Ocala, Florida 34476 on Friday, December 3, at 8:30 a.m. In accordance with Don's wishes, in lieu of flowers, donations in his memory may be made to a High School in Uganda that Don supported.  Donations should be made payable to Blessed Trinity Catholic Church with "Don Cassidy, Uganda Mission" in the memo line and mailed to the church at 5 SE 17 ^th Street, Ocala, FL 34471.