Watch the below vids see the footage that made your fave teen stars famous! (Note: We threw in the slightly-older Ian Somerhalder on the last slide for fun. You're welcome.)
We can't get over how tiny Selena and Miley are -- and how awesome Demi's audition was for Sonny! Which of them impressed you most? Any other celeb auditions tapes you're dying to see? Sound off below or tweet us @huffposthigh!