Harrelson was born on D-Day: June 6, 1944. He grew up in Hayward, California, where he attended Sunset High School, graduating in 1962. He married his first wife, Yvonne, on December 17, 1965. They later divorced, and Harrelson married Kim Battaglia in 1975. Bud's children are Kimberly, Jessica, Timothy, Alexandra, Kassandra, and Troy Joseph. Harrelson was inducted into the Suffolk Sports Hall of Fame on Long Island in the Baseball Category with the Class of 1992. He appeared as himself in a 1999 episode of Everybody Loves Raymond along with several other members of the 1969 Mets. Harrelson resides in Hauppauge, New York. In 2000, he became co-owner, Senior Vice President for Baseball Operations, and first base coach of the Long Island Ducks, an unaffiliated minor league baseball team. Harrelson was diagnosed with Alzheimer's disease in 2016.