John Daniel Costello, lovingly known as "Danny Boy," passed away peacefully on August 7, 2025, at the age of 86 in Leesburg, Virginia. Born on January 1, 1939, in Atlantic City, New Jersey, Danny led a life full of purpose, love, and service.

Danny built a home and life with his beloved wife, Pat, in Silver Spring, Maryland, and later found solace by the sea in Bethany Beach, Delaware, where he spent countless happy years. He is survived by his devoted wife Pat; sons Timothy and Matthew; cherished daughter-in-law Tamara; and grandchildren Alexander, Abigail, and Allister. He was preceded in death by his parents, Margret and Robert, and his siblings, Thomas, Robert and Margie. In his later years, he was lovingly cared for by Nuru, whose kindness and support were a blessing to the entire family.

Danny moved to Washington, DC, earning a degree in political science from Catholic University, where he began a distinguished career in public service. He served as an Administrative Assistant on Capitol Hill, running congressional offices for several Northeast legislators during a time when collaboration still defined DC politics. Following his retirement, Danny pursued his passion for civic engagement and historic preservation through his work at the National Trust for Historic Preservation.

A pillar of his community, Danny was instrumental in the founding of the Bethany Beach Farmers Market, helping to bring local growers and residents together. A true beach lover, he could be found taking a dip in the ocean every afternoon. His love of history, especially Civil War and World War II sites, was only matched by his deep affection for Irish music, which was the constant soundtrack to his life.

Danny will be remembered for his generosity, warmth, and unwavering love for his family. He was a man for others, always ready with a helping hand or a kind word.

In honor of Danny's life, the family asks that donations be made to one of his favorite causes:

The Father McKenna Center
19 Eye Street, NW
Washington, DC 20001-1425

Funeral services will take place at St. John the Baptist Catholic Church in Silver Spring, MD on September 16th at 11:00 am.