Count Sava Lukich Vladislavich-Raguzinsky (Russian: Са́вва Луки́ч Рагузи́нский-Владиславич; Serbian: Сава Владиславић Рагузински, Sava Vladislavić Raguzinski; 16 January 1669 – 17 June 1738) was a Russian and Serbian diplomat, merchant, adventurer. He was in the employ of Peter the Great. Vladislavich conducted important diplomatic negotiations in Constantinople, Rome and Beijing. His most lasting achievement was the Treaty of Kiakhta, which regulated relations between the Russian Empire and the Qing Empire until the mid-19th century. He penned a number of pamphlets, monographs, treaties and letters concerned with liberating the lands of the Slavs, then occupied by the Ottoman Empire and the forces of Leopold I.

Vladislavich was born in 1669, in the village of Jasenik near Gacko, Bosnia Eyalet, Ottoman Empire. His father, Luka Vladislavić, was a Serb landlord. The family was driven out from Gacko by the local Turks and settled in the Republic of Ragusa. His father's involvement in trade allowed Sava to be sent to the Republic of Venice, then Spain and France where he acquired broad education. The well-being of the citizens of Ragusa depended on maritime commerce; Sava Vladislavich was no exception. With his knowledge and monetary assistance from his father, he set out on his own trading venture.

A commercial project brought the young merchant to Constantinople, where, in the absence of a permanent Russian mission, he was entrusted with various tasks by the Russian foreign ministers Vasily Galitzine and Emelian Ukraintsev. It so happened that his own commercial interests always went hand-in-hand with those of the Russian government. In 1702, he made the acquaintance of Peter the Great in Azov. With an eye toward profiting from the fur trade with Russia, Vladislavich visited Moscow in the next year, but, after obtaining important privileges from the Tsar, returned to Constantinople, where he represented Russia's interests, in tandem with Pyotr Andreyevich Tolstoy, until the Battle of Poltava. It was he who purchased for the Tsar a black page, Ibrahim Hannibal, the ancestor of the great Pushkin. In 1708, he relocated to Moscow and soon received from the Tsar the lands in Little Russia, where Nezhin was made the centre of his commercial operations. In 1710, he received the rank of court adviser.

At the time Russia did not have access to the warm sea, and the ports in the Baltic were held by the English and the Dutch. Peter the Great built St. Petersburg to have a Russian port in the north, so as not to depend on the blackmail of Western traders who determined the prices of warehouses, had a monopoly on trade and kept Russia captive. However, the northern climate was severe as always, so Petar tried to go south. He asked Vladislavich to determine where ports could be built on the Black Sea coast. That project had very far-reaching consequences for the development of the Black Sea Fleet, which was made on the basis of Vladislavich's first report.

On 8 July 1708 the Battle of Poltava took place. It is alleged that Vladislavich, with his skill, de facto saved Peter in a conflict with King Charles XII of Sweden. The Swedes agreed with the Turks to attack Russia on two fronts, but Vladislavich found out about it from trusted intelligence sources and told Peter once he arrived from Constantinople in 1708. The Russian tsar was furious because the conflict had already begun to brew. The count asked him for money to bribe the Turks, who had already been bribed by the Swedes. When asked by Peter what he would do if he failed, Vladislavich answered that the only pledge he could offer was his head. Peter accepted the proposal and the matter was settled.

The "Illyrian Count" (as Vladislavich liked to style himself) maintained trade contacts with fellow Serbs and was under the impression that they would rise in revolt against the Sultan as soon as the Tsar invaded the Danubian Principalities. Having launched the invasion in 1711, Peter sent him on a mission to Moldavia and Montenegro, whose population Vladislavich was expected to incite to rebellion. Little came of these plans, despite the assistance of a pro-Russian colonel, Michael Miloradovich (the ancestor of Mikhail Miloradovich). There has been preserved an inscription from that time, in a chronicle:^{[citation needed]}

In the year 1711 Mikhail Miloradovich came to Montenegro, to the great misfortune of the Monastery and of Montenegro.... [for Vizir Kiuprili in 1714] razed Montenegro and destroyed the church and the Monastery.

From 1716 to 1722, Vladislavich resided in Venice, Italy, dividing his time between the advocacy of his own private interests and those of the Tsar. Vladislavich entertained the aristocracy of Venice as well as foreign visitors, Ernest Louis, Landgrave of Hesse-Darmstadt (1667–1739), Charles I, Landgrave of Hesse-Kassel (1654–1730), Count Girolamo of Colloredo-Waldsee, Governor of the Duchy of Milan (then under Austrian rule), Prince Teodor Konstanty Lubomirski, Anselm Franz, 2nd Prince of Thurn and Taxis, and Count Charachin.