Mary Arabella Stewart, Countess of Galloway

Arabella Stewart, Countess of Galloway (26 April 1850 – 18 August 1903), formerly Lady Mary Arabella Arthur Cecil, was the wife of Alan Stewart, 10th Earl of Galloway.

She was the daughter of James Brownlow William Gascoyne-Cecil, 2nd Marquess of Salisbury, and his second wife, the former Lady Mary Catherine Sackville-West. Her older half-brother, Robert Arthur Talbot Gascoyne-Cecil, 3rd Marquess of Salisbury, was prime minister of the United Kingdom from 1886 to 1892 and again from 1895 to 1902.

She married the future earl on 25 January 1872, a year before he succeeded to his father's titles. As Lord Garlies, he was Conservative MP for Wigtownshire, thus representing the same party as his brother-in-law.

There were no children from their marriage. The earl died in 1901, aged 65, and was succeeded in the earldom by his brother Randolph Henry Stewart, 11th Earl of Galloway. A portrait photograph of the countess, taken during the 1870s by John Watkins, is held by London's National Gallery.

The dowager countess had a London house at 17 Upper Grosvenor Street, but died at "Cuffnells", Lyndhurst, Hampshire, of pneumonia, aged 53.