9. John Sayles
John Sayles broke into screenwriting with the 1978 cult classic Piranha. Other credits include the seminal horror features The Howling and The Changeling. In his own words, Sayles believes the job of a script doctor is to help others tell their stories and he only works on scripts that may produce a film he would like to see himself. This ideal led Sayles to give an uncredited hand to smash hits like Guillermo Del Toro's Mimic and Ron Howard's Academy Award-winning Apollo 13.