Swift may have helped write a song for Harris, but he’s got plenty of songwriting talent of his own. He wrote Rihanna’s smash hit “We Found Love” way before the days of Tayvin and Nils Sjoberg.

Sia’s written songs for pretty much everybody: Britney Spears, Lea Michele, Carly Rae Jepsen, Maroon 5, Christina Aguilera — and that’s just the start. But among the most notable, which include Rihanna’s #1 smash"Diamonds"and Ne-Yo’s hit"Let Me Love You (Until You Learn To Love Yourself),“is this Beyoncé track, which pretty much means we’re forever in Sia’s debt.

Like Sia, Kesha’s written songs for a number of other artists (or they’ve gotten the ones that didn’t make it onto her own albums.) Not the case with “Till the World Ends,” however, which Kesha wrote with Spears in mind. “That song was written specifically for Britney,” she toldDigital Spy. “I put my brain in Britney Spears land and wrote that whole song for her.”

It’s the ultimate post-breakup girl power track, but Beyoncé’s hit was originally intended to be sung from themaleperspective. Ne-Yo was the one who wrote the song, and he reportedly regretted giving it up afterward.

Remember when Gomez had a band? Back then, she had an unexpected songwriter, too: Fellow pop goddessKaty Perry, who wrote this tune for Gomez and her group.

You may think of this song as a big hit for Cyrus, but it did plenty for its writer, Jessie J, too—she has said the royalties paid her rent for three years!

If you hear 1D’s acoustic melody and think, hey, that sounds like something Ed Sheeran would sing, there’s a reason why: He wrote it!

From one aughts pop icon to another. Avril Lavigne wrote this heart-wrenching record for her debut album in 2002, but it didn’t make the cut. Clarkson definitely did it justice, though!

With those distinct vocals, it’s hard to imagine any big name connected to “Forget You"besidesGreen’s. But there is one: Bruno Mars wrote the song for the formerVoicejudge.

Lady Gagacranked out hit after hit, and not just for herself. She penned this PCD tune in 2008 under her non-stage name, Stefani Germanotta.

source: people.com