CeeLo Green: Happy

Pharrell Williams originally wrote the mega-hit Happy for soul singer CeeLo Green, who actually went as far as recording a full vocal demo of the track. According to Pharrell, CeeLo's version sounded incredible, but Green's record label executives ultimately vetoed the release because he was preparing to put out a festive Christmas album instead. Left with an open track, Pharrell laid down his own vocals and created a global phenomenon.