George Plantagenet, duke of Clarence, (born Oct. 21, 1449, Dublin—died Feb. 18, 1478, London), English nobleman who engaged in several major conspiracies against his brother King Edward IV (ruled 1461–70 and 1471–83). He was the younger son of Richard, duke of York (died 1460), whose struggle to gain power precipitated the Wars of the Roses (1455–85) between the houses of York and Lancaster.

Soon after Edward IV became king in March 1461, George was made duke of Clarence, and in 1462 he was appointed lord lieutenant of Ireland. But about 1468 Clarence fell under the influence of Richard Neville, earl of Warwick, who was losing the control that he had formerly exercised over the King. In defiance of Edward, Clarence married the Earl’s daughter Isabel (July 1469). Then, in March 1470, Clarence and Warwick secretly supported an armed uprising in northern England. When Edward discovered their treachery, they fled to France but returned in September. After Edward went into exile, they put the ineffectual Lancastrian monarch Henry VI, deposed in 1461, back on the throne. But Clarence soon became disenchanted with Warwick’s management of the government. When Edward returned from exile in March 1471, the brothers became reconciled, and Clarence, who fought in the battles that led to Edward’s restoration, was made earl of Warwick and Salisbury in 1472.

After his wife died in 1476, Clarence sought to wed Mary, duchess of Burgundy. But when Edward objected to that match also, the embittered Clarence once more began scheming against his brother. Edward became convinced that Clarence was aiming at his throne. The Duke was thrown into prison, and in January 1478 the King unfolded the charges against his brother to Parliament. He had slandered the King, had received oaths of allegiance to himself and his heirs, and had prepared for a new rebellion. Both houses of Parliament passed the bill of attainder, and the sentence of death that followed was carried out secretly in the Tower of London on Feb. 18, 1478. Soon after the event, the rumour gained ground that he had been drowned in a butt of malmsey wine.

Two of the Duke’s children survived their father: Margaret, countess of Salisbury (1473–1541), and Edward, earl of Warwick (1475–99), who passed the greater part of his life in prison and was beheaded in November 1499.