Celebrities took to Twitter on Tuesday as news of Talia Castellano's passing was made public. The 13-year-old succumbed to cancer after being diagnosed five years ago on Valentine's Day with stage 4 neuroblastoma, a type of cancer that develops in the nerve tissue of children and infants. Stars such as actress KeKe Palmer, talk show host Ellen DeGeneres, and reality star Kendall Jenner  mourned her death.

The young girl appeared on "The Ellen DeGeneres Show" after becoming an Internet sensation with her makeup how-to videos, and she was an honorary face for the makeup brand CoverGirl (for which DeGeneres models) in September. During her childhood, Castellano endured rounds of chemotherapy, surgery, stem cell transplants and radiation. The strong, young girl proved that beauty comes in all forms. She chose not to wear wigs after losing all of her hair, and her slogan was "Makeup is my wig."

Castellano used YouTube as a way to inspire other women in similar daunting circumstances. She had her own channel, which she used to post makeup tutorials and words of inspiration, drawing 60,000 subscribers and more than 14 million viewers.