Hits They've Written: John Legend's "All of Me," Fergies' "Big Girls Don't Cry," Beyoncé's "If I Were A Boy"

Gad is a German-born songwriter/producer who has been putting in work since Milli Vanilli stepped on the scene (No... seriously). He's perhaps best known for co-writing Fergie's "Big Girls Don't Cry," as well as Beyonce's "If I Were a Boy." This year, he's seen tremendous success with "All of Me," a song he co-wrote with John Legend. It has been the singer's biggest hit of his ten-year career, peaking at number one on the Billboard Hot 100.