Count Anatoly Nikolaievich Demidov, 1st Prince of San Donato (Russian: Анатолий Николаевич Демидов; 5 April OS: 24 March 1813 – 29 April 1870) was a Russian industrialist, diplomat and arts patron of the Demidov family.
Born in Saint Petersburg or Moscow, he was the second surviving son of Count Nikolai Nikitich Demidov and Baroness Elisabeta Alexandrovna Stroganova. He grew up in Paris, where his father was ambassador. He served briefly as a diplomat himself in Paris (living in the hôtel built by Charles de Wailly for the sculptor Augustin Pajou, at 87 rue de la Pépinière, now the rue La Boétie), Rome and Venice. Upon his father's death in 1828, Anatole settled for good in western Europe, returning to Russia as little as possible. This attitude alienated him from tsar Nicholas I of Russia, who always had an antipathy towards him.
In 1837–38, he organised a scientific expedition of 22 scholars, writers and artists (of which Auguste Raffet and the critic Jules Janin became Demidov's friends) to southern Russia and the Crimea, headed up by Frédéric Le Play. It cost 500,000 francs and its results were published as Voyage dans la Russie méridionale et la Crimée (4 vol., 1840–1842), with 100 original lithographs by Raffet and dedicated to the tsar despite his not having taken any interest in the book (irritated as he was that most of the expedition's members had been French). Demidov also financed a trip to Russia by André Durand to relieve the peasants, the results of which were published as Voyage pittoresque et archéologique en Russie (1839). In 1840, Demidov himself published a series of articles on Russia in the Journal des Débats – these were collected as Lettres sur l’Empire de Russie (1840) with the aim of fighting certain received French ideas about Russia. Nevertheless, these works irritated Nicholas I due to their description of Russia's feudal system. In 1847 Demidov made a trip to Spain with Raffet, publishing an account of it later as Etapes maritimes sur les côtes d’Espagne (1858). In 1842, he was elected a foreign member of the Royal Swedish Academy of Sciences.