You really have to appreciate when a celebrity takes the time to do something nice for a child, especially when that child is suffering from a serious medical condition.

Kristen Bell recently left a voicemail for 6-year-old Avery Huffman, who has an inoperable brain tumor. She didn't leave the voicemail as herself, though, she left it as her character Anna from the movie "Frozen." She crowns Avery as an "honorary princess of Arendelle," and her reaction is absolutely priceless. What a sweet little girl! Check out the video: