1. Joseph Gordon-Levitt shared this photo of himself along with his co-stars Cillian Murphy, Ellen Page, and Leonardo DiCaprio, taken to promote Inception.
2. Seth Green posted this photo of himself and Alyson Hannigan taken on the set of their 1988 movie, My Stepmother Is an Alien.
3. Selma Blair shared this photo of herself hanging out with Sarah Michelle Gellar and Katie Holmes backstage at the 2000 MTV Movie Awards.
4. Jamie Lee Curtis wished Arnold Schwarzenegger a speedy recovery from open-heart surgery by posting this photo of the two of them on the set of their 1994 film, True Lies.
5. Chromeo's Dave 1 wished his little brother, DJ A-Trak, a happy birthday by posting some photos of themselves as kids.
6. Paul McCartney posted this photo of himself as a teen in Liverpool — the photo was also the cover art for his 2005 album, Chaos and Creation in the Backyard.
7. Zac Efron posted this very recent #TBT to when he had a weird beard for his upcoming movie, Beach Bum.
8. Barbra Streisand shared this photo from the London premiere of Funny Lady in 1975.
9. Sarah McLachlan posted this photo of when she performed with Cyndi Lauper at the 2005 American Music Awards.
#TBT to singing “Time After Time” with the amazing @cyndilauper at the 2005 @AMAs :)
10. Avril Lavigne shared these photos from when she did a photo shoot with Hong Kong's Prestige magazine in 2008.
#TBT to my @Prestige_HK Magazine shoot, shot by Mark Liddell 🖤