It doesn't necessarily have to be Christmas-related. Just something that you've seen, read, or maybe even personally experienced.
Here are the ones that come to mind for me...
A few years ago, I forget when and where, but Metallica was getting ready for a show. There was a woman who was pregnant and had bought tickets, but fearing for the safety of her unborn child, she decided not to go. The band somehow caught wind of it. They ordered a limo to pick her up at her house and took her out to dinner. After dinner, they invited her backstage to hang out with them for a while before the show, during which they had a big-screen TV set up so she could watch it live.
Christian Bale visited victims of the Aurora, Colorado shooting after the premier of The Dark Knight Rises.
Actor Steve Buscemi was a New York Firefighter before he became an actor. In the days following the terrorist attacks on 9/11, he returned to the fire station where he worked to help. He also did not allow any press to follow him around.
In the early 1980s, rock band Journey recorded a song that did not make it onto the album that they had just finished recording. A young fan of theirs was in a hospital in Ohio dying of cystic fibrosis. The band found out about it via the Make A Wish Foundation and flew to Ohio with a recording of the song for the boy to hear.
What are the good things you've heard of celebrities doing?