Read this and answer the question

Queen have been featured multiple times in the Guitar Hero franchise: a cover of "Killer Queen" in the original Guitar Hero, "We Are The Champions", "Fat Bottomed Girls", and the Paul Rodgers collaboration "C-lebrity" in a track pack for Guitar Hero World Tour, "Under Pressure" with David Bowie in Guitar Hero 5, "I Want It All" in Guitar Hero: Van Halen, "Stone Cold Crazy" in Guitar Hero: Metallica, and "Bohemian Rhapsody" in Guitar Hero: Warriors of Rock. On 13 October 2009, Brian May revealed there was "talk" going on "behind the scenes" about a dedicated Queen Rock Band game.

Who collaborated with Freddie Mercury on the song Under Pressure?
David Bowie