Before landing a lead role in a show, most of the time, these actors have had tons of guest-starring parts. Snagging a coveted spot as a main character doesn't happen overnight! And for some, they filmed quite a few guest-starring roles on the same networks that would eventually go on to cast them in their own shows. Trust us when we say these actors have all totally changed since they first graced your television screens!
Click through the gallery to see and the then-and-now pictures and then drop a comment below telling us who you think has changed the most!
Before Victoria Justice landed her lead role on Victorious, her first appearance on Nickelodeon was as Lola on Zoey 101.