Millions of fans tuned in last night for American Idol's two-hour, star-studded season finale. Ryan Seacrest was decked out in a tux to take in the powerful performances, later announcing 17-year-old Scotty McCreery as this year's champion — do you agree with the season 10 American Idol winner? The top 13 contestants returned to sing and dance throughout the show, as did Beyoncé Knowles, Lady Gaga, and even Idol judge Steven Tyler. Carrie Underwood arrived in a Lorena Sarbu dress then joined finalist Lauren Alaina for a duet of "Before He Cheats," and Scotty teamed up with country legend Tim McGraw on "Live Like You Were Dying." Beyonce took the stage twice, first doing a medley of her own hits like "Crazy in Love" with contestants and then a solo of her new single "One Plus One." Marc Anthony got the crowd on their feet with a Latin beat as Jennifer Lopez shook it in a hot fringed costume. Lady Gaga, U2, Tony Bennett, Jack Black, and Gladys Knight also joined in the fun before Scotty celebrated his accomplishment by belting out his first original track, "I Love You This Big."