'There was a brief trend in late 16th century France to assign famous personages or literary figures to specific court cards,' EndersGame notes.
Many Spanish and German decks historically eschewed queenly representation in favor of a separate pack of male figures. The queen cards often included the goddess Athena and Rachel, the wife of the biblical Jacob, among other ladies. (Picture cards came into being in Europe in the mid-15th century - centuries after playing cards had become popular.) French and British decks of the 16th century were said to often depict Alexander the Great, Julius Caesar, the biblical King David and Charlemagne on the king cards - representing the four great empires of Greece, Rome, the Jews and the Franks.
That's not to say that it's impossible that a deck might feature a real king the artwork varied according to the whims of card designers, manufacturers and the region in which the cards were produced.
