According to numerous reports, hip-hop superstar Nicki Minaj has agreed to join the cast of "American Idol" and serve as a judge alongside R&B legend Mariah Carey.  Rumors have tied a wide array of stars to the show since Steven Tyler and Jennifer Lopez announced they were leaving the show, but several sources say that Minaj is definitely joining, ans an official announcement will be made as soon as the contract can be worked out.  Other artists rumored to be joining the cast include Nick Jonas and Pharrell Williams, as it has also been reported that Randy Jackson will be stepping down as a judge on the show and assuming a mentoring role.  Jonas has confirmed that he is being considered on Twitter, while Williams has not discussed the matter.  "American Idol" is slated to kick off its 12th season in January.  Minaj is no stranger to "American Idol," as she performed her hit single "Starships" on the show last season.  Check out a clip of that performance below.