Henry Stacy Marks (13 September 1829 – 9 January 1898) was an English artist who took a particular interest in painting birds.
Henry Stacy Marks was born in London as the fourth child of John Isaac Marks and Elizabeth née Pally. His father was a solicitor who later became a coach builder. Henry enrolled at the Royal Academy Schools in about 1851 and first exhibited at the Royal Academy in 1853. When his father's business failed, Henry Marks had to support his mother, his three younger brothers and, from 1856, his new wife, Helen Drysdale. He did this by supplementing his income from painting by carrying out decorative work for various patrons. These included the Minton works, for the stained glass makers Clayton and Bell, by designing a frieze for the outside wall of the Royal Albert Hall, and for the house of the artist Lawrence Alma-Tadema. Marks' most important patron was Hugh Grosvenor, 1st Duke of Westminster and he worked on decoration for the duke's house, Eaton Hall, Cheshire, between 1874 and 1880. For this house he painted two canvasses 35 feet (11 m) long of Chaucer's pilgrims, and twelve panels of birds.
Marks became a member of the St John's Wood Clique in 1862. As his career progressed, he became increasingly interested in painting birds. Possibly his most famous painting is A Select Committee (1891) which is now in the Walker Art Gallery. He was elected as a member of the Royal Academy following his painting Convocation, which was exhibited in 1878. Most of his paintings of birds were watercolours, which he exhibited at the Old Watercolour Society or at the Fine Art Society.
His first wife died in 1892 and the following year Marks married Mary Harriet Kempe, who was also a painter. He died in his London home and was buried in Hampstead Cemetery. His estate amounted to a little over £9,600.