Betty White was a beloved actress, comedian, and well-known animal advocate. On Monday (January 17), fans are honoring the late icon by donating to local animal shelters in her honor.

White died on New Years Eve at age 99, just a few weeks before her centennial celebration. “Even though Betty was about to be 100, I thought she would live forever,” White's close friend and agent Jeff Witjas previously confirmed in a statement to PEOPLE. “I will miss her terribly and so will the animal world that she loved so much...”

Her love for the animal world inspired the Betty White Challenge, which quickly trended on social media on White’s 100th birthday. CBS News pointed out that Twitter user Lisa Powell previously wrote, in response to Ryan Reynolds’ reaction to his former costar’s death, that fans should “donate something to your local animal shelter on Betty's birthday on January 17th in her honor! It's the least we can do to still celebrate & honor Betty's love of animals!! #RIPBetty #BettyWhite #ripbettywhite #BettyWhiteChallenge #BettyWhiteDay.” Though it isn’t clear whether the challenge stems from Powell’s tweet or from someone else, the idea caught on.