An unexpected guest vocal: Marianne Faithfull on the Metallica song "The Memory Remains." A star in the '60s, this collaboration helped revive her career.
The Nicolette Larson hit "Lotta Love" was written by Neil Young, who recorded a very different version of the song.
Katy Perry co-wrote Iggy Azalea's hit single "Black Widow." Perry was originally going to sing on the track, but she couldn't fit it into her schedule, so Rita Ora provided the sung vocals instead.
"Happy Xmas (War Is Over)" is based on billboards John Lennon and Yoko Ono posted two years earlier declaring "War Is Over! If You Want It."
Demi Lovato recorded a Spanish version of her song "Skyscraper," but she doesn't speak Spanish. She performed it on a Latin music awards show with help from a teleprompter.
Cyndi Lauper's hit "All Through The Night" was written and originally recorded by Jules Shear, who also wrote "If She Knew What She Wants" by the Bangles.
The Doobies guitarist and lead singer, Tom wrote the classics "Listen To The Music," "Long Train Runnin'" and "China Grove."
Beef with Bon Jovi? An unfortunate Spandex period? See if you can spot the true stories in this Metallica version of Fact or Fiction.
With his X-wife Exene, John fronts the band X and writes their songs.
Phil was a songwriter, producer and voice behind many Philadelphia soul classics. When disco hit, he got an interesting project: The Village People.
Shows like Dawson's Creek, Grey's Anatomy and Buffy the Vampire Slayer changed the way songs were heard on TV, and produced some hits in the process.
The Def Leppard frontman talks about their "lamentable" hit he never thought of as a single, and why he's juiced by his Mott The Hoople cover band.