The story
From king + maker, originally used in the 16th century in “Warwick the Kingmaker”, an epithet of Richard Neville, 16th Earl of Warwick (1428–1471), a key figure in the Wars of the Roses whose actions led to King Henry VI being deposed in 1461 and Edward IV appointed in his place, then Edward IV being replaced by Henry VI again in 1470.
Etymology from Wiktionary, CC BY-SA 4.0.