In Memoriam: Marc E. Kellenberger
Marc E. Kellenberger, a visionary leader in community engagement, philanthropy and nonprofit development, passed away on Feb. 24, 2025, leaving a lasting legacy of service, generosity and commitment to building a more just and equitable world.
Marc’s career as a development professional and nonprofit executive spanned over 35 years, during which he served numerous educational institutions, art organizations and human service agencies. Most notably, as senior vice president and chief development officer for Arizona Children’s Association, he helped drive unprecedented fundraising and programmatic success.
In 2004, Marc co-founded The Phoenix Philanthropy Group with his partner in life and business, Richard Tollefson. He took great pride in its growth and impact, helping nonprofits achieve financial strength and expand their reach. He spearheaded the Nonprofit Leadership Initiative and Forum, engaging key leaders to address Arizona’s most pressing social issues. This effort led to the ongoing Economic Vitality Study, highlighting the nonprofit sector’s influence on the state. He also played a key role in securing Phoenix Philanthropy’s membership in the Giving Institute, the nation’s premier authority on philanthropy.
Marc’s generosity extended far beyond his profession. He helped lead Arizona’s first $1 million AIDS WalkArizona and gala fundraisers for Arizona AIDS Project, engaging top business, political and community leaders in support of HIV/AIDS causes. He was a dedicated volunteer and champion of organizations such as Friends of the Phoenix Public Library, Central Arizona Shelter Services, the City of Phoenix Human Rights Commission, and the City of Phoenix Arts and Culture Commission, where his advocacy helped bring some of the city’s most renowned public art installations to life. A strong supporter of social justice, he played a pivotal role in medical ethics, anti-bullying and anti-gun violence initiatives, earning him the Arizona Human Rights Fund’s statewide Human Rights Award and the Malta Center’s Humanitarian of the Year Award.
One of Marc’s proudest moments came in 2020, when the Arizona Community Foundation named the Kellenberger + Tollefson Center for LGBTQ Philanthropy in honor of his and Richard’s transformative legacy gift and leadership. The Center is dedicated to advancing justice and opportunity for LGBTQ individuals and the communities they call home.
Marc is survived by his partner of nearly 40 years, Richard Tollefson; sisters Mary Heintz, Melinda Leman, Margie Johnson and Melissa Genz and their families; and his beloved cat, Lily.
A celebration of his life will be announced at a later date. In lieu of flowers, donations in Marc’s memory may be made to the LGBTQ Leaders Impact Fund at the Kellenberger + Tollefson Center for LGBTQ Philanthropy, a component fund of the Arizona Community Foundation.
