Diana Nicole DeGarmo (born June 16, 1987) is an American singer and Broadway actress. She finished as the runner-up on the third season of the reality/talent-search television series American Idol, narrowly missing the win by about 2% (approximately 1.3 million votes) out of over 65 million votes. At 16, DeGarmo was the second youngest contestant among the set of finalists in the third season after John Stevens; she was a junior at Shiloh High School in Snellville, Georgia.
She voiced Cosmo in his new singing voice in the The Fairly OddParents episode "Fairy Idol" so he could compete on the show with the song "Gimme the Wand". This was the result of a training video called How to Sing Like Diana DeGarmo that he watched prior to the performance.