Britney Spears: "Quicksand"
Britney Spears' chart-topping 2008 album, Circus, includes a bonus track called "Quicksand" Gaga cowrote with Fernando Garibay. Gaga also wrote her hit "Telephone" for this album, but it didn't make the cut and wound up a hit for herself, with some help from Beyonce.
New Kids on the Block: "Full Service"
New Kids on the Block's 2008 comeback album, The Block, included a guest feature from Gaga on the track "Big Girl Now" but also included her writing credits on the New Edition-featuring "Full Service," which she cowrote with frequent collaborator RedOne and Donnie Wahlberg.
Michael Bolton: "Murder My Heart"
Michael Bolton and Gaga may seem like an unlikely pairing but the '80s icon brought the budding pop star onboard to help with his 2008 album One World One Love on the ballad "Murder My Heart." When Newsweek asked Gaga about the collaboration, she recalled, "The record label called me and said, 'Michael is doing a new album, and who better to write an '80s love song than Lady Gaga?'" We'll say they were right.
Adam Lambert: "Fever"
Adam Lambert's 2009 debut album, For Your Entertainment, got some of Gaga magic touch on its debaucherous fourth single, "Fever."
Jennifer Lopez: "Hypnotico"
"Hypnotic" was originally written by Gaga with RedOne, Akon, Claude Kelly and Tami Chynn for Chynn's second studio album in 2007, but the album was never released and the song nearly never saw the light of day. But once Jennifer Lopez began working with RedOne on her 2011 album Love?, the song found new life.