Before he was a singing high school student, Zac Efron was a boy genius studying to be a doctor. In space. Back in 2002, a 14-year old Efron made a guest appearance in the cult-classic sci-fi show “Firefly,” Joss Whedon’s space western. The soon-to-be “High School Musical” star played a young Simon, who, played by Sean Maher, was a crew member of Serenity, the smuggling ship of Captain Malcolm Reynolds (Nathan Fillion). Efron can be seen playing with some sort of tablet device and cursing in a strange language. It was his first major role, and four years later, his star would explode on the Disney Channel. [Source]