American Idol Finale: The Returns! The Performances! The Winner!

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Carrie Underwood stopped by. 

So did Jennifer Hudson, Simon Cowell and even President Barack Obama... sort of.

There were plenty of memorable moments from the American Idol series finale, even before Trent Harmon was crowned the winner.

Who put on the best performance? Whose return took you most by surprise? What stood out to you the most, for either a good reason or a very bad one?

Relive the American Idol finale below...

1. Co-Hosts Reunite

Co-Hosts Reunite
That's Brian Dunkleman. The original American Idol co-host came out on the finale and hugged Ryan Seacrest.

2. President Obama Addresses American Idol Viewers

President Barack Obama made a video appearance on the American Idol series finale. Yes, THAT President Barack Obama!

3. Kara DioGuardi, Tamyra Gray and Jordin Sparks Sing a Medley

Kara DioGuardi, Tamyra Gray and Jordin Sparks all returned to the American Idol stage to sing a medley of pop hits on the series finale.

4. Carrie Underwood and Keith Urban Duet

Carrie Underwood and Keith Urban! On one stage! Check out their performance on the American Idol finale.

5. William Hung "Bangs" Out on American Idol Stage Again!

William Hung just had to "Bang" out his memorable Ricky Martin cover one more time. Check out his return here to American Idol.

6. American Idol Acoustic Medley

American Idol broke it down for this finale performance. Watch Amber, Carly, Casey, Clay, Jessica, Katherine and Ruben perform without the help of any instruments.

7. WGWG Tandem Pays Tribute to David Bowie

Rest in peace, David Bowie. American Idol paid tribute to the late, iconic singer at this point in the finale.

8. Jennifer Lopez Performs on American Idol

Jennifer Lopez can do more than just judge. Watch her sing on the American Idol finale in this fun video.

9. Carrie Underwood Performs on American Idol Finale

If you saw Carrie Underwood perform "Something In The Water" on the American Idol finale, you know why she's among the top two or three stars the show has ever produced.

10. Simon Cowell Returns!

Simon Cowell Returns!
He kept his appearance a secret, but Simon Cowell gave us a cameo on the American Idol finale, showing up to embrace Paula Abdul and Randy Jackson.

11. American Idol Soul Medley

Soul Patrol! Look at all the American Idol alums who returned for this soulful performance on the finale.

12. Jennifer Hudson, Fantasia Barrino and LaToya London on Stage

Jennifer Hudson, Fantasia Barrino and LaToya London belt out a version of "Bridge Over Troubled Water" in this clip from the American Idol finale.

13. And the Winner Is...

Trent Harmon was crowned the winner of American Idol Season 15. See him react to the news here.

Wait! There's more! Just click "Next" below:

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American Idol Quotes

Brooke White's tears come from the authentic, good soul that she is. Her heart was breaking because she was overwhelmed with the experience she had with the show and the gift that it brought.

Paula Abdul [after Brooke White was eliminated on season seven]

I read some of this online this morning and just for the record, the rumors — they’re not true. She’s part of our family and we love her.

Ryan Seacrest [on rumor of Paula Abdul being drunk on the show]