Thomas de Berkeley, 1st Baron Berkeley (1245 – 23 July 1321), aka The Wise, was an English baron, soldier and diplomat.Thomas de Berkeley was born in 1245 at Berkeley Castle in the English county of Gloucestershire, the son of Sir Maurice de Berkeley and Isabel FitzRoy. Isabel FitzRoy was the granddaughter of John, King of England, by his cousin and mistress, Adela de Warenne, daughter of Hamelin de Warenne and Isabel de Warenne, 4th Countess of Surrey.