After 15 seasons, "American Idol" is coming to an end Thursday night, and the broadcast will have more than a couple of surprises. The finale will include Ryan Seacrest's former co-host Brian Dunkleman as well as contestant William Hung, who infamously auditioned with the Ricky Martin hit "She Bangs" in Season 3.

For the finale, Dunkleman will reportedly open the show and Hung will perform a song. Fans can also expect to see all of the former winners as well as most of the top three contestants from all 15 seasons of the series for one big performance. The singing competition will even welcome back former judges, including the original three: Simon Cowell, Paula Abdul and Randy Jackson.

When "American Idol" first started all the way back in 2001, Dunkleman and Seacrest co-hosted the program together. However, Dunkleman quit the show before it returned for Season 2 in order to pursue a career in acting.

"I was very upset about it for a long, long time," Dunkleman said about his decision to leave "American Idol" before it became such a huge hit. "You got to make up your mind that either you are going to be that angry guy for the rest of your life, or you gotta move on. It's taken me a long time to get there."

Hung became a pop culture phenomenon after his audition in 2004. Just a civil engineering student at the University of California at Berkeley at the time, he won over the hearts of fans and managed to get his own record contract before retiring from music in 2011.

"You can't sing, you can't dance, so what do you want me to say?" judge Cowell told Hung after his "American Idol" audition.

In adition to all the guests that will be in Hollywood for the last episode of the show that gave the world stars like Carrie Underwood and Jennifer Hudson, the original American Idol herself, Kelly Clarkson, will appear in a pretaped message since she is getting ready to deliver her second child.

The two-hour "American Idol" series finale airs Thursday, April 7, at 8 p.m. ET on Fox.