Seth Rogen co-wrote the first draft of Super Bad at age 13.

The Canadian born actor, Seth Rogen, found success through Judd Apatow who believed in him. Rogen was cast in Apatow's cult hit Freaks and Geeks. Apatow could tell Rogen would be a comedic star and continued to give Rogen roles, but networks just didn't see Rogen as a leading man.

Rogen wasn't too surprised as he always figured he'd gain much of his success through writing. He co-wrote the first draft of Super Bad when he was just 13. He continued writing and was on a writing staff for people like Judd Apatow and Sacha Baron Cohen. He continued writing and eventually was given the chance to show off his leading acting skills in his own comedies and those of Apatow and others.

(Source)