Too Much Diva Alert! Judge Mariah Carey took the stage on the finale of Season 12 of 'American Idol' tonight (May 16), as did former judge Jennifer Lopez, who served during Seasons 10 and 11.

Mimi elected to perform a medley of hits that included 'Vision of Love,' 'Make It Happen,' 'Hero,' 'We Belong Together' and her new single '#Beautiful,' among others, while Randy Jackson played guitar! Mimi was a vision in a white, mermaid-style dress. We think she may have been lip-syncing.

She was followed by the equally divalicious Lopez, who debuted her new single 'Live It Up,' with a little help from her pal Pitbull. It also sounded like a lip-synced performance, we hafta say. J. Lo sure did look extra sexy, though.

Psy also danced his butt off to 'Gentleman.' Few have the dancefloor skills, moves or techniques that Psy has.

Watch Jennifer Lopez Perform 'Live It Up'

Watch Psy Perform 'Gentleman'