Mary Elizabeth Kler Heisinger of Greenville died Monday April 5, 2021 at St. Peter’s Hospital in Albany after a short illness. Born in New Brunswick, New Jersey, Mary was the daughter of the late Dr. Joseph H. Kler, M.D. and Elizabeth Vaughan Kler. She graduated from Kent Place School (Summit, NJ) and from the University of Rhode Island with a BA in English and a minor in History. In her youth, Mary enjoyed equestrian sports, gardening with her mother, and fishing with her father. She was an avid learner, lover of history, and rarely without a book in her hand. Extremely active in community projects throughout her lifetime, she served as a member of the board of New Brunswick’s East Jersey Olde Town, Vice President of the Pratt Museum’s Board of Directors in Prattsville, NY, Chairperson of Community Action of Greene County, President of Greenville’s Friends of the Library, Trustee of the Greenville Library (Honored as Trustee of the year in 2003 by the Mid-Hudson Library System) and sat on the board of the Greene County Historical Society. She was recognized by the NYS Assembly in 2011 for her work in the community and library. Passionate about history, she was a wanderer of museums and a member of the DAR and the Huguenot Society of America. She organized the Civil War Round Table and numerous other book and discussion groups. Even in her hobbies, Mary enthusiastically took on leadership roles. She was President of the Women’s Golf League at the Windham Country Club and formed a women’s golf league at Thunderhart Country Club in Greenville. She was a member of the Clematis Garden Club, serving as president in 2015. She was also a member of a women’s bowling league in Ravena where she continued to bowl until a few months ago. Mary loved her family, friends, and community. She never slowed down and delighted in social gatherings and intellectual pursuits. Her competitive spirit shone while skeet shooting with her husband or playing backyard croquet with her family. She was tenacious in her drive to live life to the fullest and will be sorely missed by many. Mary lost her husband and lifelong partner, Walter R. "Bob" Heisinger, in 2012. She is survived by her children, Thomas R. Heisinger (Kathleen) and Elizabeth A.H. Stewart (Marc); her grandchildren Jennifer A.H. Greathouse (Jesse), Meaghan E.H. Siekman (Michael), Joseph E. Heisinger, and Amelia E. Stewart; and great-grandchildren, Patrick and Morrighan Siekman and Sadie Greathouse. She is predeceased by her son, Edward K. Heisinger and her sister, Marjorie Kler Freeman. A private internment will take place at Saratoga National Cemetery and a celebration of her life will take place later this year. Those who would like to remember Mary in a special way may contribute in her memory to The Greenville Public Library, PO Box 8, Greenville, NY 12083. Arrangements by A.J. Cunningham Funeral Home, Greenville. Condolences can be posted at ajcunninghamfh.com.