Ottoline Violet Anne Cavendish-Bentinck Morrell (1873-1938) was the daughter of Lieutenant-General Arthur Bentinck and his second wife, Augusta Mary Elizabeth. Ottoline had three older brothers and a half-brother from Bentinck's first marriage. She spent the early years of her childhood in the sheltered manner of upper class children of the time, raised largely by a nurse and servants, spending time at both the country house and the summer house in London. Ottoline's father had expectations of succeeding his cousin, the fifth Duke of Portland, which were disappointed when Bentinck died first in 1877. This left the family in rather straitened circumstances until the Duke of Portland settled the succession of the title and an allowance on Ottoline's half-brother in 1878, and then died a year later. The sixth Duke of Portland and his family moved into the family seat at Welbeck a few weeks later.

Ottoline had no playmates of her own age at Welbeck and her education was left in the hands of a governess who taught her to read, write, and memorize Bible verse, but very little else. Ottoline grew introspective and introverted as time passed. When she was sixteen, the Duke married and Ottoline's mother removed herself and Ottoline from Welbeck to a small house in Chertsy. For the next three years Ottoline lived in a sort of exile with her mother. During this time she developed an almost fanatical interest in religion, wearing drab clothing, fasting, and following the precepts of Thomas àKempis's book

When Ottoline was nineteen, it was decided by her mother and the Duke that she should come out. She was squired through the London season with all due pomp and circumstance. However, she lacked the confidence to enjoy the attention this brought her and she retired back to the country afterwards to continue caring for her now seriously ill mother. In 1893 Ottoline and her mother traveled to Italy, returning via Paris to England, where Lady Bolsover fell almost immediately into a coma and died.

Returning to live at Welbeck, Ottoline occupied herself by teaching Bible classes to the servants and farmhands and performing good works. She convinced her brother to send her on several trips to the continent and to support two attempts at university education, both of which failed.

In 1900 Ottoline met attorney Philip Morrell, and married him two years later. In 1906 Philip gained a liberal seat in the House of Commons and the Morrells moved to a house in Bloomsbury at 44 Bedford Square. It was here that Ottoline delivered twins, but only the daughter Julian survived. It was also at 44 Bedford Square that Ottoline began to establish herself as a preeminent literary and political hostess in London society. Her political guests came largely from the Liberal party and included Winston Churchill and Herbert Asquith. On the literary and artistic side her acquaintances were numerous and included Lytton Strachey, Henry James, Virginia and Leonard Woolf, Vanessa and Clive Bell, Dora Carrington, Dorothy Brett, D.H. and Frieda Lawrence, and T.S. Eliot. She also had affairs with Augustus John, Henry Lamb, and a protracted relationship with Bertrand Russell.

The Morrells moved out of London in 1915 to a manor east of Oxford at Garsington. Philip's public anti-war stance had gotten him into trouble with the Liberal party and eventually he lost his seat in the House over the issue, but continued to assist conscientious objectors with legal advice and even found agricultural jobs for a few at Garsington Manor. In the country Ottoline continued her social efforts, inviting numerous guests to visit and providing a short-term home for more than one starving artist. The Morrells maintained Garsington for eleven years before the expense and the relative isolation of country living caused them to look again towards a house in town. In 1927 they moved back to Bloomsbury, this time to 10 Gower Street, and there they stayed for the last eleven years of Ottoline's life.

Throughout her life Ottoline suffered from severe headaches and other illnesses. She traveled to many spas and resorts around Europe seeking treatment. She maintained the strong religiosity of her youth, doing good works and caring for a great number of people. In May 1937 she suffered a stroke and spent three months in a clinic at Tunbridge Wells recovering. In April of 1938 she died in the same clinic of heart failure.