The Evstafi class were a pair of pre-dreadnought battleships of the Imperial Russian Navy built before World War I for the Black Sea Fleet. They were slightly enlarged versions of the Russian battleship Potemkin, with increased armour and more guns. Numerous alterations were made as a result of experience in the Russo-Japanese War of 1904-1905 that seriously delayed the completion of the two ships.

They were the most modern ships in the Black Sea Fleet when World War I began and formed the core of the fleet for the first year of the war, before the newer dreadnoughts entered service. They forced the German battlecruiser SMS Goeben to disengage during the Battle of Cape Sarych shortly after Russia declared war on the Ottoman Empire in late 1914. Both ships covered several bombardments of the Bosphorus fortifications in early 1915, including one where they were attacked by the Goeben, but they managed to drive her off. Later, Evstafi and Ioann Zlatoust were relegated to secondary roles after the first dreadnought entered service in late 1915, and were subsequently put into reserve in 1918 in Sevastopol.

Construction of Ioann Zlatoust began on 14 November 1903, well before the formal keel-laying ceremony on 13 November 1904. Progress was relatively quick, despite the disruptions caused by the 1905 Revolution, and she was launched on 13 May 1906. Fitting-out, however, was considerably delayed by a number of changes made as the navy digested the lessons of the Russo-Japanese War. For example there was a period of seven months in 1907 where virtually no work was done on the ship and she was not completed until 01 April 1911. Ioann Zlatoust's turrets had originally been intended for a reconstruction of the elderly pre-dreadnought Chesma, but they were diverted to Ioann Zlatoust after that reconstruction was cancelled.

Before the beginning of World War I the Black Sea Fleet experimented with concentrating fire from several ships under the control of a "master ship". They had to be identically armed and were equipped with additional radio gear to transmit and receive range and deflection data. Ioann Zlatoust became the master ship for the Black Sea Fleet, working with Evstafi and Pantelimon.

Two weeks after the Russian declaration of war on the Ottoman Empire on 2 November 1914, the Black Sea Fleet, comprising the pre-dreadnoughts Evstafi, Ioann Zlatoust, Pantelimon, Rostislav, Tri Sviatitelia, and three cruisers were escorted by three destroyers and 11 torpedo boats set out on 15 November to bombard Trebizond. They did this successfully on the morning of 17 November and they turned west to hunt for Turkish shipping along the Anatolian coast before setting course for Sevastopol later that afternoon. They were intercepted by the German battlecruiser Goeben and the light cruiser SMS Breslau the following day in what came to be known as the Battle of Cape Sarych. Despite the noon hour the conditions were foggy and the capital ships initially did not spot each other. Evstafi was the lead ship, but held her fire until Ioann Zlatoust, the master ship, could see Goeben. When the gunnery commands were finally received they showed a range over 3,700 m in excess of Evstafi's own estimate of 7,000 m, so Evstafi opened fire using her own data before Goeben turned to unmask its broadside. Evstafi scored a hit with her first salvo as a 12-inch shell partially penetrated the armour casemate protecting one of Goeben's 15-centimetre secondary guns. It detonated some of the ready-use ammunition, starting a fire that burnt out the casemate and killed its crew. That was, however, the only hit on Goeben, although it caused her to disengage from the Russian squadron. Ioann Zlatoust merely fired six shells herself as only her forward turret could see Goeben.

On 9 January 1915 Breslau and the Ottoman cruiser Hamidiye encountered the Russian fleet while returning from a mission in the eastern part of the Black Sea. Breslau hit Evstafi's forward turret, temporarily putting it out of action, and the two cruisers escaped using their superior speed. Evstafi and Ioann Zlatoust served as the covering force for several bombardment missions of the Bosphorus between 18 March and 9 May 1915. The two earlier bombardments were uneventful, but the 9 May bombardment provoked a reaction as Goeben intercepted the Russian battleships after they had been spotted by the Ottoman destroyer Numune-i Hamiyet. Both forces turned on parallel courses and opened fire at the range of 15,900 m. Neither side scored a hit although Goeben had multiple near-misses on Evstafi. Vice Admiral Andrei Eberhardt ordered his ships to make only 5 knots while Goeben was making 25 knots. Goeben was unable to cross the T of the Russian ships, despite its superior speed, as they were continually turning. This manoeuvre bought enough time that Tri Sviatitelia and Pantelimon were able to rejoin the other two ships before they could start shelling the Ottoman forts. Pantelimon hit Goeben twice before the German ship broke contact after 22 minutes of firing. With the fleet assembled Admiral Eberhardt attempted to pursue the enemy battlecruiser, but was unsuccessful.

On 1 August 1915, Ioann Zlatoust and all the other pre-dreadnoughts were transferred to the 2nd Battleship Brigade, after the dreadnought Imperatritsa Mariya entered service. On 1 October the new dreadnought provided cover while Ioann Zlatoust and Pantelimon bombarded Zonguldak and Evstafi shelled the nearby town of Kozlu. Both Evstafi-class ships participated in the second bombardment of Varna in May 1916.

Evstafi and Ioann Zlatoust were reduced to reserve in March 1918 in Sevastopol. Immobile, they were captured there by the Germans in May 1918 and handed over to the Allies the following December. The British wrecked both ships' engines 22-24 April 1919 when they left the Crimea to prevent the advancing Bolsheviks from using them against the White Russians. They were captured by both sides during the Russian Civil War, but were abandoned by the White Russians when they evacuated the Crimea in November 1920. The ships was scrapped in 1922-23, although they were not struck from the Navy List until 21 November 1925.