In honor of his birthday, Robin Williams’ little girl posted a sweet message to her late father

Actor Robin Williams (R) and daughter Zelda pose at the premiere of Columbia Picture's 'RV' at the Village Theater on April 23, 2006 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)

Actor Robin Williams (R) and daughter Zelda pose at the premiere of Columbia Picture's 'RV' at the Village Theater on April 23, 2006 in Los Angeles, California. (Photo by Kevin Winter/Getty Images)

Thursday marked what would have been actor Robin Williams' 65th birthday, and his daughter misses him more than ever.

Zelda Williams penned a beautifully written Instagram post in honor of her father's birthday.

"Still not really sure what to do on days like today… I know I can't give you a present anymore, but I guess that means I'll just have to keep giving them in your name instead," she wrote alongside the goofy picture of her beloved father with his arms around his three children, Zelda, Zak and Cody.

"This year, I tried to help three causes you cared about in one; rescue dogs, people suffering from disabilities, and our nation's wounded veterans, so I donated to freedomservicedogs.org. They rescue pups from shelters and train them so that they can be paired with someone in dire need of their help and companionship. Thought you'd get a kick out of furry, four legged friends helping change the world, one warrior in need at a time"

Williams signed off her note with a final message to her father.

"Happy birthday Poppo. Shasha, Zakky, Codeman and I all love you and miss you like crazy. Xo."