For many, the costume-clad visitors provided a distraction from the hospital surroundings and gave those fighting serious illnesses added energy and some laughter.
"Some kids need visits from their heroes to help them heal," said Laurie Strongin, founder and executive director of The Hope for Henry Foundation, which sponsored the "Superhero Extravaganza" at the hospital.
"A visit from a superhero can transform a kid’s life. It can give them strength they need to get through a rough day, or a painful procedure, or break the monotony of a long hospitalization."
The party along the hospital pediatric unit was also held in honor of the late Lenny Robinson, who partnered with the foundation for nearly 10 years, and dressing up as Batman to visit sick children at local hospitals to bring them moments of joy.
Robinson died in a car accident in August when his custom-made "Batmobile" broke down on a Maryland roadside.
While Batman wasn't there, the cupcakes, balloons and visits from other superheroes elicited plenty of smiles from the children, as young as 2.
Jimmy A. of Virginia was about to be discharged from the hospital after his fourth round of chemotherapy for brain cancer. But when he heard the party outside his hospital room, Jimmy, 12, asked to stay longer in order to meet his favorite superhero, Spiderman.
"That was a lot of fun," Jimmy said, smiling from his bed after the visit where he was given his own mask, a few toys and a pep talk from Spiderman. "I wasn't expecting all of that."
When asked what Spiderman told him at his bedside, Jimmy responded, "He's trying to tell me to keep fighting through the pain."