Do you know who each king is in a deck of cards?

For a period, starting in the 15th century, French playing-card manufacturers assigned to each of the king cards names taken from history or mythology. This practice had largely disappeared by the 19th century. The most common names for the kings were:

• King of Spades: David (a biblical king)
• King of Hearts: Charles (presumably after Charlemagne)
• King of Diamonds: Caesar (presumably after Julius Caesar, dictator of the Roman Republic)
• King of Clubs: Alexander (king of Macedon)

Source: Wikipedia