'The Voice': Celebrity MentorsJuly 28, 2012 at 1:04 AMLink CopiedRead full article1 / 12The Voice Celebrity Mentors, Billy J. ArmstrongBillie Joe Armstrong on Team Christina, Season 3AP ImagesHere's a roundup of all the big-name music stars who've joined coaches Christina Aguilera, Adam Levine, Blake Shelton, and Cee Lo Green on "The Voice" as mentors. View comments