Meaning

noun English statesman; during the War of the Roses he fought first for the house of York and secured the throne for Edward IV and then changed sides to fight for the house of Lancaster and secured the thr

noun an important person who can bring leaders to power through the exercise of political influence

originFrom 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 3.0