Leonard Litwin

Litwin was married to Ruth Litwin; she died in 2014. They had two daughters: Carole Litwin Pittelman, acting as the company's president, and Diane Litwin Miller.

Leonard Litwin died on April 2, 2017, at the age of 102.

Notwithstanding his success in real estate, Litwin remained in the nursery business, operating Woodbourne Cultural Nurseries, Inc., in Melville, on Long Island, NY. He was turning the nursery into an arboretum of over 200 acres. With fellow developer Don Zucker, he co-founded the Litwin-Zucker Research Center for the Study of Alzheimer's Disease at The Feinstein Institute for Medical Research in Manhasset, New York, and substantially supported research at several hospitals. Additionally, Litwin established The Litwin Foundation.

In 2012, at age 97, he was rated as the highest individual donor to New York State politicians in the past year, with donations amounting to $700,000. He avoided caps on his donations by using his limited liability companies (LLCs). He gave state Republicans $436,500 and Governor Andrew Cuomo $76,000. William Street Associates is an LLC which once was headed by Leonard Litwin. The firm made a donation to Peter Vallone's campaign in 2000. In 2017, the Crohn's & Colitis Foundation renamed its Broad Medical Research Program to the Litwin IBD Pioneers Initiative after Litwin for his lifelong support for the IBD community.