Dramatis Personae
KING EDWARD IV
EDWARD, PRINCE OF WALES
afterwards KING EDWARD V, King's son
RICHARD, DUKE OF YORK, King's son
GEORGE, DUKE OF CLARENCE, King's brother
RICHARD, DUKE OF GLOUCESTER,
afterwards KING RICHARD III, King's brother
A YOUNG SON OF CLARENCE (Edward, Earl of Warwick)
George Plantagenet, 1st Duke of Clarence, 1st Earl of Salisbury, 1st Earl of Warwick, KG, lived from 1449 to 1478, when he was convicted of treason against Edward and apprently  drowned in a vat of wine. 
 
 George Plantagenet, 1st Duke of Clarence. Image via  Wikimedia Commons. 
 We first see Clarence in the  first scene,  as he’s being carted off to prison for having a first name beginning with “G”, since it has been prophesied that someone beginning with “G” will murder the king’s children. 
 
 Encyclopedia Britannica : “George Plantagenet, Duke of Clarence”. Retrieved Online.
King Richard III Characters of the Play