Jean-Gilbert-Victor Fialin, duc de Persigny (11 January 1808 – 12 January 1872) was a diplomat and of the Second French Empire.
Fialin was born at Saint-Germain-Lespinasse in the Loire, where his father was Receiver of Taxes, and was educated at Limoges. He entered Saumur Cavalry School in 1826, becoming Maréchal des logis in the 4th Hussars two years later. The role played by his regiment in the July Revolution of 1830 was regarded as insubordination, resulting in Fialin being dismissed from the army. He then became a journalist, and after 1833, a strong Bonapartist, assuming the style vicomte de Persigny, said to be dormant in his family.
He was involved in the abortive Bonapartist coups at Strasbourg in 1836 and at Boulogne-sur-Mer in 1840. After the second coup, he was arrested and condemned to twenty years' imprisonment in a fortress, commuted to mild detention at Versailles. There he wrote a book to prove that the Egyptian pyramids were built to prevent the Nile from silting up. The book was published in 1845 under the title De la destination et de l'utilité permanente des Pyramides.
During the 1848 Revolution, Fialin was arrested by the Provisional Government. After his release, he played a prominent part in securing Prince Louis-Napoleon Bonaparte's election to the presidency. Together with Morny and Marshal Saint Arnaud he plotted the Restoration of the Empire, and was a devoted adherent of Napoleon III. He succeeded Morny as French Minister of the Interior in January 1852, and became Senator later that year. He resigned in 1854, and was appointed Ambassador to London the next year, a post he occupied with a short interval (1858–1859) until 1860, when he resumed the portfolio at the Interior Ministry. But the growing influence of his rival Rouher prompted his resignation in 1863, after which the Emperor created him a Duke.