Francis Charles Seymour-Conway, 3rd Marquess of Hertford KG GCH PC (March 11 1777–March 1 1842) was the son of Francis Seymour-Conway, 2nd Marquess of Hertford.
On May 18 1798, he married Maria Fagniani. They had three children:
- Lady Francis Maria Seymour-Conway (d. 1822)
- Captain Richard Seymour-Conway, 4th Marquess of Hertford (1800–1870)
- Lord Henry Seymour-Conway (1805–1859)
Lord Hertford was the prototype for the characters of the Marquess of Monmouth in Benjamin Disraeli's 1844 novel, Coningsby and the Marquess of Steyne in William Makepeace Thackeray's 1848 novel, Vanity Fair.
He was a considerable art collector, as were his son and grandson; many of his pictures are in the Wallace Collection which they founded.