Margaret Bentinck, Duchess of Portland

Her Grace The Duchess of Portland
Margaret Cavendish Bentinck, Duchess of Portland by Christian Friedrich Zincke, 1738
Personal details
Born	11 February 1715 Welbeck Abbey, Nottinghamshire
Died	17 July 1785 Bulstrode Park, Buckinghamshire
Nationality	British
Spouse	William Bentinck, 2nd Duke of Portland
Children	Elizabeth Thynne, Marchioness of Bath Henrietta Grey, Countess of Stamford William Cavendish-Bentinck, 3rd Duke of Portland Lady Margaret Bentinck Lady Frances Bentinck Lord Edward Bentinck
Parent(s)	Edward Harley, 2nd Earl of Oxford and Mortimer Lady Henrietta Holles
Occupation	Art and natural history specimens collector

Margaret Cavendish Bentinck, Duchess of Portland (11 February 1715 – 17 July 1785) was the richest woman in Great Britain of her time, styled Lady Margaret Harley before 1734, Duchess of Portland from 1734 to her husband's death in 1761, and Dowager Duchess of Portland from 1761 until her own death in 1785.

The duchess, an heiress on a huge scale had the largest natural history collection in the country, complete with its own curator, the parson-naturalist John Lightfoot, and the Swedish botanist Daniel Solander. Her collection included costly art objects such as the Portland Vase. Her ambition for her collection was for it to contain and to describe every living species.

She was a member of the Blue Stockings Society, a group of social intellectuals led by women and founded by her great friend Elizabeth Montagu.