Thomas de Berkeley, 1st Baron Berkeley (1245 – 23 July 1321), The Wise,feudal baron of Berkeley, of Berkeley Castle in Gloucestershire, England, was a peer, soldier and diplomat. His epithet, and that of each previous and subsequent head of his family, was coined by John Smyth of Nibley (d.1641), steward of the Berkeley estates, the biographer of the family and author of "Lives of the Berkeleys".
Thomas de Berkeley was born in 1245 at Berkeley Castle in Gloucestershire, the son of Sir Maurice de Berkeley, feudal baron of Berkeley, by his wife Isabel FitzRoy, a granddaughter of King John (1199-1216), through his son Richard FitzRoy, by his cousin and mistress Adela de Warenne, daughter of Hamelin de Warenne and Isabel de Warenne, 4th Countess of Surrey.
He fought in the Battle of Evesham in 1265. He inherited the feudal baron of Berkeley in 1281 following the death of his father and on 28 June 1283 was created 1st Baron Berkeley by writ of summons to Parliament by King Edward I (1272-1307). In June 1292 he was a commissioner to examine the claims to the crown of Scotland. He was on an embassy to France in January 1296 and held the office of Vice-Constable of England in 1297. He fought in the Battle of Falkirk on 22 July 1298 and was present at the Siege of Caerlaverock, Scotland, in July 1300. He was on an embassy to Pope Clement V in July 1307. He fought in the Battle of Bannockburn on 24 June 1314, where he was taken prisoner, and obliged to pay a large sum for his ransom.