A Korean king invented an entire alphabet from scratch to fight illiteracy

In 1443, King Sejong of Joseon Korea personally devised Hangul, a phonetic alphabet whose consonant shapes were designed to mimic the mouth positions used to pronounce them. He promulgated it in 1446 specifically so commoners who couldn't read Chinese characters could become literate. It remains one of history's only writing systems with a single named inventor and a documented design rationale.

— Gari Ledyard, The Korean Language Reform of 1446 — Monograph, 1966; Hangul promulgated 1446