Viscount Portman

Viscount Portman, of Bryanston in the County of Dorset, is a title in the Peerage of the United Kingdom. It was created in 1873 for the former Lord Lieutenant of Somerset and Liberal Member of Parliament Edward Portman, 1st Baron Portman. He had already been created Baron Portman, of Orchard Portman in the County of Somerset, in 1837, also in the Peerage of the United Kingdom. His son, the second Viscount, represented Shaftesbury and Dorset in the House of Commons as a Liberal. As of 2014 the titles are held by the latter's great-great-grandson, the tenth Viscount, who succeeded his father in 1999.

The Portman family post-1728 are descended in the male line from a junior line of Berkeley of Stoke Gifford one of whose members married the daughter of Joan Portman, the great-granddaughter of Sir William Portman, Lord Chief Justice of England between 1555 and 1557. He had acquired land in Marylebone, London, which - through the later housing developments of Henry William Portman, who turned it into the Portman Estate - is still the base of the Portman family wealth. The judge's grandson was created a baronet in 1612 (see Portman Baronets). On the death of the first baronet's grandson Sir William Portman, 6th Baronet in 1690 without progeny, the family estates passed under a settlement to the latter's first cousin Henry Seymour (d.1728), MP, 5th son of Sir Edward Seymour, 3rd Baronet of Berry Pomeroy, Devon, by his wife Anne Portman, the second daughter of Sir John Portman, 1st Baronet. Seymour took the surname Portman in lieu of his patronymic, but left no issue. The property then devolved upon another cousin, William Berkeley (d.1737) of Pylle, Somerset, who also took the surname Portman in lieu of his patronymic. His great-grandson was Edward Berkeley Portman (1771–1823), MP for Dorset and father of Edward Portman, 1st Viscount Portman.

The family seat was Bryanston House, near Bryanston, Dorset.