3. Edward Kitsis/Adam Horowitz
A great deal of Onces success is due to the minds behind the scenes, and the next few folks on this list are a big part of that behind the scenes mastery. Edward Kitsis and Adam Horowitz are television collaborators and writers who have stormed onto the scene in recent years, thanks largely to their work on a little show called Lost from 2005-2010. Previous credits for the duo include Felicity (created by a relative unknown by the name of J.J. Abrams) and the short-lived Birds of Prey. Their work both in and out of genre television has served them well as creators of, and executive producers/writers for, Once Upon A Time.