1. Ryan Reynolds shared this adorable photo of him and his brother Jeff.
2. Luke Evans shared this behind-the-scenes photo from the filming of The Hobbit.
One ringtone to rule them all. Me and Orlando Bloom and Peter Jackson relaxing on the set of #TheHobbit. #TBT
3. Janet Jackson celebrated the 20th anniversary of her beautiful tribute song to the victims of AIDS, "Together Again."
4. Madonna remembered her friend, Keith Haring, on World AIDS Day.
5. Rob Lowe posted these behind-the-scenes photos from his 1983 film, The Outsiders.
6. Penélope Cruz shared some photos from when she modeled for Ralph Lauren.
7. David Duchovny posted this photo of when he got to hang out with Prince Charles.
#tbt Hanging out with Prince Charles. @RoyalFamily 🦊 🤴
8. The iconic Smokey Robinson shared this photo of himself posing with his fellow icons The Supremes.
In good company 😎 #TBT
9. Raven-Symoné posted a clip from her 1993 music video for her song "That's What Little Girls Are Made Of."
10. Cindy Crawford shared some behind-the-scenes photos from her 1995 film, Fair Game.
11. Mark Ruffalo posted this pic from his theater days.
Back in my theater days in LA. Thanks @DelShores for the throwback. #tbt