There are a few things that are sacred in life. This isn't to be disputed as it seems logical enough.
Aside form the obligatory answers of love and family and french fries, one of those things for me are posters.
Posters as we know them today are about 200 years old. According to historian Max Gallo, posters had been strung up all over the place for a variety of reasons. Their main purpose, as one could surmise, is advertising of either a political or mercantile natures.
Around the 1870s, with the perfection of color lithography, is when the heyday of posters came about and it hasn't looked back since. Whether they hang in your bedroom, outside a theater or search for them online is almost irrelevant.
Posters are designed to capture your imagination (and the money from your wallet as a result) and entice you like someone or something. They remain an effective piece of advertising and, for the most part, are just cool.
Every WWE pay-per-view since the very first WrestleMania has had an associating poster to hype the event. The reasons that people like certain posters vary as much as what they want on their pizza. Somethings just are what they are.
As such, this isn't meant to be a definitive list of the coolest of all time by any sort of measurable metrics or system. These are just posters that I like.