From the longer Wikipedia page 
Richard Neville, 16th Earl of Warwick KG]] (22 November 1428-14 April 1471), known as Warwick the Kingmaker, was an English nobleman, administrator, and military commander. The son of Richard Neville, 5th Earl of Salisbury, Warwick was the wealthiest and most powerful English peer of his age, with political connections that went beyond the country's borders. One of the Yorkist leaders in the Wars of the Roses, he was instrumental in the deposition of two kings, a fact which later earned him his epithet of "Kingmaker" to later generations.
Through fortunes of marriage and inheritance, Warwick emerged in the 1450s at the centre of English politics. Originally a supporter of King Henry VI, a territorial dispute with the Duke of Somerset led him to collaborate with Richard, Duke of York, in opposing the king. From this conflict he gained the strategically valuable post of Captain of Calais, a position that benefited him greatly in the years to come. The political conflict later turned into full-scale rebellion, where in battle York was slain, as was Warwick's father Salisbury. York's son, however, later triumphed with Warwick's assistance, and was crowned King Edward IV. Edward initially ruled with Warwick's support, but the two later fell out over foreign policy and the king's choice of Elizabeth Woodville as his wife. After a failed plot to crown Edward's brother, George, Duke of Clarence, Warwick instead restored Henry VI to the throne. The triumph was short-lived however: on 14 April 1471 Warwick was defeated by Edward at the Battle of Barnet, and killed.
Warwick had no sons. The elder of his two daughters, Isabel, married George, Duke of Clarence. His younger daughter Anne, after a short-lived marriage to King Henry's son Edward of Westminster, who died in battle at the age of 17, then married King Edward's younger brother Richard, Duke of Gloucester, who later became King Richard III.
Warwick's historical legacy has been a matter of much dispute. Historical opinion has alternated between seeing him as self-centred and rash, and regarding him as a victim of the whims of an ungrateful king. It is generally agreed, however, that in his own time he enjoyed great popularity in all layers of society, and that he was skilled at appealing to popular sentiments for political support.