Mary Jane Seacole (born Grant; 23 November 1805 – 14 May 1881) was a British-Jamaican nurse, healer and businesswoman who set up the "British Hotel" behind the lines during the Crimean War. She described this as "a mess-table and comfortable quarters for sick and convalescent officers", and provided succour for wounded servicemen on the battlefield, and nursed many of them back to health. She had met the most famous nurse in history Florence Nightingale for 5 minutes during the Crimean War. Coming from a tradition of Jamaican and West African "doctresses", Seacole displayed "compassion, skills and bravery while nursing soldiers during the Crimean War", through the use of herbal remedies. She was posthumously awarded the Jamaican Order of Merit in 1991. In 2004, she was voted the greatest black Briton.

Mary Seacole relied on her skill and experience as a healer and a female doctor from Jamaica. Schools of nursing in England were only set up after the Crimean war, the first being the Florence Nightingale Training School, in 1860 at St Thomas' Hospital in London. Seacole was arguably the first nurse practitioner.

Hoping to assist with nursing the wounded on the outbreak of the Crimean War, Seacole applied to the War Office to be included among the nursing contingent but was refused, so she travelled independently and set up her hotel and tended to the battlefield wounded. She became popular among service personnel, who raised money for her when she faced destitution after the war.

In 1858 a four-day Fundraising Gala took place on the banks of the River Thames, to honour Mary Seacole. Crowds of about 80,000 attended, including veterans, their families and Royalty.

After her death, she was largely forgotten for almost a century but was subsequently recognised for her success as a woman. Her autobiography, Wonderful Adventures of Mrs. Seacole in Many Lands (1857), is one of the earliest autobiographies of a mixed-race woman, although some aspects of its accuracy have been questioned by present-day supporters of Florence Nightingale. The erection of a statue of her at St Thomas' Hospital, London, on 30 June 2016, describing her as a "pioneer", has generated controversy and opposition from Nightingale enthusiasts, such as Lynn McDonald, and others researching the period.