Family spokesman Christopher Winters says 8-year-old Delaney Brown of West Reading "passed away quietly with her loving family by her side" early Christmas morning.
He says the family is requesting privacy now "to celebrate their daughter's life and to mourn her loss."
Delaney, nicknamed Laney, was diagnosed in May with a rare form of leukemia.
Thousands gathered outside her home Saturday night to fulfill her wish for a huge holiday singalong.
An update posted on the "Team Laney" Facebook page says, "My heart breaks right now. Our little angel on earth earned her pink glittery angel wings in heaven. ... I miss her so much already."
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