The “American Idol” season finale reunited past winners for a special rendition of judge Lionel Richie’s “We Are the World.” The hit singing competition aired its Season 18 finale on Sunday where it not only crowned Just Sam as the winner, but it debuted judge Katy Perry’s new single “Daisies” and aired an historic broadcast of the song Richie co-wrote for charity alongside Michael Jackson in the 1980s.