Marc E. Kellenberger
December 16, 1955 – February 24, 2025
Marc E. Kellenberger, a visionary leader in community engagement, philanthropy, and nonprofit development, passed away peacefully on February 24, 2025, leaving an enduring legacy of service, generosity, and unwavering commitment to building a more just and equitable world.
From an early age, Marc dedicated himself to the power of nonprofits to transform communities. As a teenager, he chaired the Walk to End World Hunger in Elgin, Illinois, and served on the boards of the YMCA, the Elgin Committee on Recycling, and Elgin Community College. This early passion for service set the foundation for a lifelong career devoted to strengthening nonprofit organizations and enhancing their ability to create meaningful change.
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, Marc was the long-time senior vice president and chief development officer for Arizona’s Children Association, where he helped guide the organization to an unparalleled level of fundraising and programmatic success.
In 2004, Marc co-founded The Phoenix Philanthropy Group with Richard Tollefson, his partner in life and business. Marc took immense pride in the growth of Phoenix Philanthropy and found great reward in knowing that his expertise had helped nonprofits achieve financial strength and expand their impact. He was the driving force behind the Nonprofit Leadership Initiative and Forum, a statewide initiative to engage and activate key nonprofit, business, and government leaders in a collective process to address Arizona’s most pressing social issues. This initiative resulted in the ongoing Economic Vitality Study, which demonstrates the size, economic impact, and influence of the nonprofit sector on the state. Marc was also instrumental in securing Phoenix Philanthropy’s membership in the prestigious Giving Institute, the preeminent source on the state of American philanthropy.
Marc’s generosity of spirit extended well beyond his professional endeavors. He played a pivotal role in leading the first $1,000,000 AIDS Walk Arizona and gala fundraisers for Arizona AIDS Project, the first events to actively engage prominent allied philanthropists and business, political, and community leaders in support of HIV/AIDS-related causes. He was a dedicated volunteer leader and supporter of organizations such as the 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 ardent support of public art resulted in some of the city’s most renown art installations. He supported and hosted fundraisers for a wide variety of political candidates and issues and was instrumental with medical ethics, anti-bullying, and anti-gun violence initiatives in Arizona. He was a long-standing member of Social Venture Partners Arizona and helped develop fundraising initiatives on a global basis. His advocacy earned him the Arizona Human Rights Fund’s statewide Human Rights Award and the Malta Center’s Humanitarian of the Year award – testaments to his deep commitment to social justice and equality.
One of Marc’s proudest moments was in 2020 when the Arizona Community Foundation named the Kellenberger + Tollefson Center for LGBTQ Philanthropy in honor of Marc and Richard to recognize their transformative legacy gift and invaluable leadership to the community. The Center was established to contribute to an Arizona and society that advances justice and opportunity for LGBTQ people and the communities where they live.
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 companion, Lily, the cat. Marc was known for his love for the beach and unique global travel adventures.
A celebration of Marc’s life will be announced at a later date.
In lieu of flowers, donations may be made in Marc’s honor to the Arizona Community Foundation’s Kellenberger + Tollefson Center for LGBTQ Philanthropy online here.
Checks made payable to:
Arizona Community Foundation
Memo: K+T Center for LGBTQ Philanthropy
Mail to:
K+T Center for LGBTQ Philanthropy
c/o Arizona Community Foundation
2201 E. Camelback Rd., Ste. 405B
Phoenix, AZ 85016