Edgar Allan Poe
Poe claimed in 1841 that any cipher could be solved, then wrote a story in which a cipher falls to frequency analysis.
In the essay A Few Words on Secret Writing (1841) in Graham's Magazine, Poe argued that any cipher could be solved by someone with enough patience, and invited readers to send him theirs. Two years later he published The Gold-Bug (1843), in which a treasure map is hidden in a substitution cipher that is solved by counting letters. The claim holds for simple substitution. It does not hold for polyalphabetic systems, which were not broken in a general way until Kasiski published his method against the Vigenère cipher in 1863.