"Kingmaker" is a term originally applied to the activities of Richard Neville, 16th Earl of Warwick, during the Wars of the Roses in England. The term has come to be applied more generally to a person or group that has great influence in a royal or political succession, without being a viable candidate. Kingmakers may use political, monetary, religious, and/or military means to interfere in the succession. Examples include:
Warwick, the Kingmaker.
Nogai Khan, Mamai Khan, and Edigu Khan, who influenced succession in the Golden Horde.
Baron Carl Otto Mörner.
In game theory
In game theory, a kingmaker is a player who lacks sufficient resources or position to win at a given game, but possesses enough remaining resources to decide which of the remaining viable players will eventually win.
By analogy, "Kingmaker" is also used in some countries to refer to those with the ability to influence the selection of political leaders.
Modern politicians known as "Kingmaker" include: James Farley who orchestrated the gubernatorial and presidential elections of Franklin D. Roosevelt 1928-1940.
K. Kamaraj was instrumental in making Lal Bahadur Shastri and Indira Gandhi as Prime Ministers of India in the year 1964 and 1966 respectively.
Sonia Gandhi who seems to many the de facto Prime Minister of India; named as a kingmaker on numerous occasions, Time magazine named her as such and called her India's leader in all but title.
Dick Morris who orchestrated the gubernatorial and presidential elections of Bill Clinton.
Kakuei Tanaka in Japanese politics.
Graham Richardson in Australian politics.
Nepali Congress party chief Girija Prasad Koirala has been described as a kingmaker in Nepal with the election of Madhav Kumar Nepal.[http://www.zeenews.com/news534020.html]
Fred Malek has been described as a kingmaker for the Republican Party in the United States.[http://www.politico.com/news/stories/0509/22736.html]
David Axelrod has been described by U.S. News and World Reports as a "reporter turned kingmaker" with respect to the ascendancy of Barack Obama. [http://www.usnews.com/articles/news/obama/2009/05/19/obamas-power-players-axelrod-helps-refine-the-presidents-message.html]
Bakili Muluzi has been described as a kingmaker in Malawi.[http://www.nyasatimes.com/national/3424.html]
The character Leon Fortunato from the Left Behind series of novels is often described as a kingmaker.
Marcus Jefferson Wall, the antagonist of much of the Matador series by Steve Perry is called the Kingmaker, and controls the President of the Galactic Federation (Wikipedia)