Lieutenant Colonel William Joseph Duncan, USAF (Ret.), was born on October 2, 1945, in St. Louis, Missouri, to a loving family. He passed away peacefully following a brief illness on January 7, 2026, while visiting family in Arkansas.

Bill was humble, generous, brilliant, fun-loving, and deeply respected by all who knew him. His Catholic faith and values guided every aspect of his life - shaping how he loved his family, conducted his work, made thoughtful decisions, and lived each day with purpose. He loved great food, European soccer, jazz, classic rock, Broadway shows, Caribbean beaches, and was an avid Sudoku player. He truly believed that a life well lived is one well loved, valuing experiences over possessions.

Bill graduated from Christian Brothers College High School in St. Louis in 1964, where he was active in ROTC, beginning a lifelong commitment to service, leadership, and country. He earned a Bachelor of Science degree from Saint Louis University Parks College in 1967 and later a master’s degree from Florida State University.

Bill proudly served in the United States Air Force for 20 years, retiring with the rank of Lieutenant Colonel. His career took him across the United States and around the world, including assignments at Cape Canaveral, FL during the “Space Race” of the 1960s and 1970s, Virginia, California, Alabama, England (RAF Menwith Hill), and Maryland. His work supported vital missions for the National Reconnaissance Office, the National Security Agency, the Pentagon and the National Space program. He played a significant role in deploying and managing numerous satellites and spacecraft critical to our nation’s defense.

Following his military retirement, Bill continued to serve his country working in the private sector within the Intelligence Community, including Raytheon, Scitor (where he helped open the Maryland office) and Ocean Riders. The final chapter of his career was spent at Legato LLC, where he tackled the nation's most demanding defense challenges with unwavering skill. To his peers and the community, he was nothing short of a national treasure, and the loss of his unparalleled expertise, friendship and mentorship leaves a void that will be deeply felt.

Although he received numerous military awards and professional accolades, Bill was most proud of his family and the personal and work relationships he cultivated throughout his life. He was a devoted husband, nurturing father, adoring grandfather, loyal friend, and an exceptional role model and mentor. A man of integrity with a strong work ethic, he gave constant love, encouragement, and unwavering support to his family, friends, and colleagues.

His time stationed in England with his young family sparked a love of travel and exploration that stayed with him throughout his life. Over the years, he delighted in sharing his favorite places, restaurants, wine and other recommendations with friends and strangers alike. He joyfully revisited many of his favorite places with his beloved granddaughters to show them the beauty of the world and inspired them to dream boldly and live fully.

Bill was preceded in death by his parents, Eleanor (nee Henkenius) and James Duncan, and his brothers, James and Patrick. He is survived by his beloved wife of 55 years, Carol (nee Swepston); his children, James (Wendy) Duncan and Elizabeth Duncan; his grandchildren, Addison and Megan; and his sister, Arlette Szczepan (Roger), and their family.

Although Bill (also known as “Poppi”) will be deeply missed by all who were fortunate enough to know and love him, we find comfort in knowing that our Poppi is now at peace and watching over us from heaven.

Family and friends may visit on Thursday January 22, 2026 from 4:00pm-7:00pm at Barranco Severna Park Funeral Home & Cremation Care,P.A. 495 Ritchie Hwy Severna Park, MD 21146. A Mass of Christian Burial will be Celebrated on Friday January 23, 2026 at 10:30am at St John the Evangelist Roman Catholic Church 689 Ritchie hwy Severna Park, MD 21146. A reception will follow at Chartwell Country Club 1 Chartwell Dr, Severna Park, MD 21146 from 12:00pm-3:00pm. Burial with honors at Arlington National Cemetery at a later date.

In lieu of flowers, the family asks that donations be made in Bill’s honor to organizations they support: Heifer International, the USO and World Central Kitchen.