King Charles VI of France, known as “Charles the Mad,” ruled from 1380 to 1422—and believed he was made of glass. Gripped by the rare “glass delusion,” he feared shattering on contact and wore reinforced clothing to protect himself.

His mental health declined in his twenties, leading to paranoia and instability at court, as nobles competed for power during his erratic reign. Despite early efforts to bring peace to France, his delusions often overshadowed his leadership.

His reign remains one of history’s most unusual examples of how personal struggles can shape a nation’s fate.