William & Henry Bentinck
Several members of the Bentinck family are buried in the Ormond vault at the eastern end of Henry VII's chapel in Westminster Abbey. None have monuments but their names and dates of death were added to the vaultstone in the late 19th century.
William Bentinck, 1st Earl of Portland
Hans Willem, from the Netherlands, was a son of Bernhard Bentinck and his wife Anna and was page of honour to William, Prince of Orange and fought with him in several campaigns. He was envoy to England to arrange the marriage of William to Princess Mary and accompanied him when he assumed the throne as William III, joint monarch with Mary II. His titles were Baron Cirencester, Viscount Woodstock and Earl of Portland. His first wife was Frances (sometimes wrongly called Anne), daughter of Sir Edward Villiers and sister of the 1st Earl of Jersey. His second was Jane Temple, widow of Sir John Berkeley (neither are buried in the Abbey) William was buried on 3rd December 1709.
Henry Bentinck, Duke and Earl of Portland
The eldest surviving son of William and Frances he was Marquis of Tichfield, Viscount Woodstock, Baron Cirencester and in 1716 Duke of Portland. He commanded a troop of Life Guards, was a Member of Parliament and Governor of Jamaica 1721-1726. He died there on 4th July 1726 and was buried with his father on 3rd November. In 1704 he married Lady Elizabeth Noel.
William Bentinck, 2nd Duke of Portland
He was a Fellow of the Royal Society and a trustee of the British Museum. In 1734 he married Margaret-Cavendish Harley, daughter of the 2nd Earl of Oxford. She was a great patron of the arts and sciences. He was buried on 8th May 1762 and she on 30th July 1785. Their son William became Prime Minister.
Oxford Dictionary of National Biography 2004, for Margaret and her son
"William Bentinck and William III" by Marion Grew, 1924