1. The Avengers
Sometimes you need to pull out the bells and whistles to market a film as ambitious as The Avengers. Sometimes, if you're lucky, all you have to do is make a good series of movies to precede it. The Avengers was simultaneously the hardest and yet the easiest film to market: the hardest, because these heroes were freshly minted in the movie public's eyes and still relatively untested, but easiest because each subsequent film helped market the overall premise of the film's core concept. Starting with an end credit tag included with Iron Man, "The Avenger Initiative" became a driving throughline through all other Marvel films. This lead to characters from the other films in the Marvel Cinematic Universe popping up where they weren't expected. Hey kids, Tony Stark's going to recruit The Hulk! Who's hammer fell to the Earth in New Mexico, drawing the attention of our intrepid Agent Coulson? Wait, was that REALLY Captain America's shield that Tony used to prop up his generator? Easter Eggs, direct references, and post credit tag sequences all built this universe where superheroes were coming out of the woodwork, and a non-government entity wanted to form the ultimate defense strategy by using their individual strengths (and weaknesses) to defeat insurmountable enemies. The best part about this whole strategy, and also the worst, is that it relied on the strength of the other films to carry across the message. While we were watching the heroes we'd grown up with finding their strengths, sooner or later Nick Fury and his crew would come knocking on their door and offering them a chance at greatness. By time The Avengers was released in 2012, a full backstory was fleshed out that lead up to one of the biggest film events of the modern era, as well as a built in audience that only grew with each subsequent film's release. Most impressively, Marvel had succeeded in doing what D.C. had only dreamed of, putting them ahead of the long game when it comes to Super Hero franchises. With The Avengers planting the flag, D.C.'s Justice League was left in the dust, hoping to one day catch up to Marvel's beautiful coup. One would hope that this ingenious strategy would be a lesson to this, and most other films that build off of the pre-existing strength of a franchise.