Leslie Joseph Hellenack

Leslie J. Hellenack of Belmont passed away peacefully on April 5, 2026, at the age of 97. Born March 5, 1929, in the town of Herkimer, NY he enjoyed many adventures with his siblings and spent time exploring the Adirondack Mountains.  He proudly served his country in the United States Air Force during the Korean War, where he shared his aptitude for logic and numbers by teaching mathematics to his fellow servicemen. He graduated from Fairleigh Dickinson University in 1962 with a bachelor’s degree in mechanical engineering. He also obtained an MBA degree in 1970 from NYU. His education and knowledge led him to hold many positions in several companies including MW Kellogg, Peat Marwick & Mitchell (now KPMG), Mitrol Inc and International Data Corp. He eventually formed his own company, Hawthorne Consulting Group Inc.  His love of travel took him all over the globe with a particular fondness for Italy and the landscapes of Europe.  He was a patron of the arts, an avid reader, loved sailing and enjoyed sharing good food, wine and conversations with friends and family.

He was predeceased by his parents Roy and Gertrude (Bennett), Hellenack, his brother Thomas Hellenack, his sister Mary Jean Hellenack, his first wife Barbara (Totten) Hellenack and his son Brian Hellenack. He is survived by his beloved wife of 17 years, Bonnie R. Gray. His sons Mark Hellenack (Zoe Liston) of Hopkins MN and Scott Hellenack (Linda) of Wake Forest, NC and his granddaughter Alyson Hellenack McGregor (Justin) of Matthews, NC. 

Relatives and friends are kindly invited to attend a Funeral Service at Pilgrim Church 25 South Main Street Sherborn on Monday May 11th at 10am.  Followed by burial at Pine Hill Cemetery Sherborn with military honors. In lieu of flowers donations in memory of Leslie may be made to Sierra Club 50 Federal Street 3rd Floor Boston, MA 02110.  

https://www.sierraclub.org/massachusetts

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