Sonia Mary Orwell (née Brownell, 25 August 1918 – 11 December 1980) was a British editor and archivist. She was the second wife of Eric Arthur Blair, commonly known by his pen name George Orwell. Born in British India, Brownell's family moved to London, where she was educated at Sacred Heart Convent in Roehampton. In her twenties, she became involved with the founders of the Euston Road School, as model for William Coldstream, Victor Pasmore and Claude Rogers.

She met Orwell while working at the literary magazine, Horizon. After the death of his wife, Eileen Blair, when Orwell was dying from tuberculosis, they married in hospital on 13 October 1949. Their marriage lasted for three months until his death. As his sole heir and literary executor, Brownell was protective of his estate for years after his death. She established the George Orwell Archive at University College London in 1960. With Ian Angus, she edited The Collected Essays, Journalism and Letters of George Orwell in 1968. Brownell is believed to be the model for Julia, the heroine of Nineteen Eighty-Four.

Brownell was born on 25 August 1918 at Mesra Thaua, in Ranchi, British India, the daughter of Charles Neville Brownell (1882–1918), a Calcutta freight broker, and Beatrice Edith Binning (1890–1959). Her father died in a suspected suicide when she was four months old. Her older sister, Beatrice (known as Bay) was deeply affected by the loss at the age of four. Following his burial in Calcutta, the family sailed back to England to be with their relations. On 5 January 1920, her mother married Edgar Geoffrey Dixon (1880–1953), a chartered accountant. The family returned to Calcutta, where they lived at 1 Old Ballygunge Road, Mayfair. A younger half brother, Michael, was born in 1921.

Brownell was raised as a Roman Catholic and at the age of six was sent to boarding school from 1 September 1924 at the Sacred Heart Convent in Roehampton, London (now part of Roehampton University), which she despised. She hated the nuns who ran the school, felt deeply lonely, and was held in contempt by other students. By 1924, Dixon's alcoholism made him abusive and put a strain on the family. Brownell was taken out of boarding school. In 1927, Dixon's drinking ruined his career when he was thrown out of the Calcutta Club and had to resign. The family moved to Liverpool, England and Brownell was sent back to boarding school. In 1930, Bay left school and the marriage broke up. Her mother earned money by managing boarding houses.

She left school in the summer of 1935, after winning a school leaver's prize for an essay she wrote titled "Man is a Builder". Her mother sent her, at the age of 17, to Neuchâtel, Switzerland to take courses at the college in French literature and language. There Brownell was involved in a tragic accident, while staying with a Protestant pastor and his daughter, Madeleine. She went sailing with Madeleine and two Swiss boys when the boat overturned due to a squall. The other teenagers were unable to swim and drowned. Brownell attempted to save the remaining boy, but he struggled and pulled her down with him, so that she had to struggle free and was unable to save him. Afterwards she blamed herself for his death, telling her half-brother, Michael, that she had held him under the water. In the summer of 1936, she returned to London, due to being affected by the tragedy.

After learning French in Switzerland, she took a secretarial course. She moved into a flat in Fitzrovia, London, where she socialised with Caitlin Macnamara and Vivien John. In the summer of 1938, she travelled around Eastern Europe with her new friends, Serge Konovalov, who would become professor of Russian at the University of Oxford, and Eugène Vinaver. They spent the holiday travelling by car around Yugoslavia, Bulgaria, Romania and Poland. Vinaver helped her to pay her rent by offering her a typing job, which involved transcribing and editing the copy text for the first edition of the Winchester Le Morte d'Arthur. Her London flat was located in an artists' neighbourhood, so her long blonde hair was quickly noticed by the local artists like Lawrence Gowing. She became the model for the founders of the Euston Road School, William Coldstream, Victor Pasmore and Claude Rogers, and became friends with artists such as Francis Bacon and Lucian Freud. She was introduced to the school by Adrian Stokes, with whom she had a three week affair and after, had a relationship with Pasmore. The painters nicknamed her the Euston Road Venus. In April 1939, she went to Paris with four artist friends, Graham Bell, Olivier Popham, Rodrigo Moynihan and his wife, Elinor Bellingham-Smith. After returning to London, Brownell became close friends with Coldstream just after her 21st birthday in August 1939. On 3 September, war with Germany was declared. The Euston Road School closed and she went to live with the Moynihans at Monksbury, Hertfordshire, where she taught their son, Rodrigo. Coldstream courted her and she visited him secretly in London in December where they continued their relationship. She took a job teaching the son of a wealthy family in Hampstead and found a room in Goodge Street. Coldstream completed a portrait of Brownell at the studio of Vanessa Bell at 8 Fitzroy Square. By the late 1930s, she had renounced being a Roman Catholic.

Through Coldstream she met Stephen Spender and Cyril Connolly, who were the co-editors of the literary magazine Horizon, and also the arts benefactor Peter Watson. Brownell made a proposal to them for the contents of an issue about young artists, but in April 1940, they turned it down. In the spring and summer of 1940, she continued to help at the magazine while searching for work. In July 1940, she was employed at a mobile first aid unit and from early September, when bombs began falling on London, she worked with rescue crews recovering survivors. She accepted a marriage proposal from Coldstream but broke off the engagement and their affair was ended by spring 1941. She worked as a secretary for John Lehmann in 1941 and at the Ministry of War Transport. In 1945, she returned to Horizon as an editorial secretary and acted as working partner for Connolly in his absence. Connolly and Watson often left her in charge of running the magazine and there she developed a reputation for having a difficult temperament. Brownell's biographer and friend, Hilary Spurling, wrote that this criticism was the result of her "trespassing on traditionally masculine critical and intellectual preserves".

Brownell worked as an editor for Weidenfeld and Nicolson from 1951 to 1956, where she was involved in publishing Saul Bellow, Nigel Dennis, Elizabeth Hardwick, Dan Jacobson, and Mary McCarthy. In 1962, she organised the Writers' Conference at the Edinburgh Festival. In 1964 and 1965 she worked in Paris as co-editor of Art and Literature. In 1966, she translated Days in the Trees, by Marguerite Duras, for the Royal Shakespeare Company.