Clay Aiken, ''Always and Forever'' (Season 2)
How could you forget Clay Aiken's audition?! He looked like such a dork — and then he said he could've made Top 10 the previous season — and I was like, get out of here. Then he sang! Wow! I learned not to judge auditioners' appearances, and he's been my favorite Idol ever since. —Kaf

Clay Aiken's audition: Watch it on YouTube

See the 12 auditions EW.com's Michael Slezak named as the best he's ever seen on American Idol