We all have favorite papers in our own respective areas of theory. Every once in a while, one finds a paper so astounding (e.g., important, compelling, deceptively simple, etc.) that one wants to share it with everyone. So list these papers here!
Embarrassingly, I think I’ve only read one of these, the fun Ken Thompson one about a compiler Trojan horse.
See also: 10 Papers Every Programmer Should Read (At Least Twice) and the 6.033 reading list.