The Shortest Papers Ever Published (2016)
Although these short papers are fun, I think the most interesting papers are those that are both important and concise. One of my favorite examples is Josh Nash's proof of the existence of Nash Equilibria (which is a foundational concept in game theory and arguably won Nash a Nobel):http://www.pnas.org/content/36/1/48.fullIt's less than a full page in the original journal.