John of Beaumont (1288 – 11 March 1356) was a younger brother of count William III of Holland.
John of Hainault bought the heerlijkheid (comparably to the English Barony) of Beaumont, located in the southern Netherlands, for his son.
On 23 July 1313 Noordwijk and Beverwijk were raised to hoge heerlijkheid (literally: high barony), which placed them amongst the most important fiefs in Holland.
At the battle of Warns William IV was killed by the frisians while John of Beaumont barely managed to escape.
This made his grandson John II, Count of Blois heir to the expensive possessions in Holland and Zeeland.
Ships named after Bloys of Treslong include John is a character in Les Rois maudits (The Accursed Kings), a series of French historical novels by Maurice Druon.
Sir John of Hainault is a character in Edward II, a play by Christopher Marlowe.