The Ersatz Yorck class was a group of three battlecruisers ordered but not completed for the German Kaiserliche Marine in 1916. The three ships had originally been ordered as additions to the Mackensen class, but developments abroad, particularly the British Renown-class battlecruisers, led to the navy re-designing the ships. The primary change was an increase of the main battery from eight 35-centimeter (14 in) guns to eight 38 cm (15 in) weapons. Work on the first ship had already begun by the time the navy decided to re-design the ships, so the design staff was constrained by the need to use the material already assembled.

The battlecruiser was a type of capital ship of the first half of the 20th century. These were similar in displacement, armament and cost to battleships, but differed in form and balance of attributes. Battlecruisers typically had thinner armour and a somewhat lighter main gun battery than contemporary battleships, installed on a longer hull with much higher engine power in order to attain greater speeds. The first battlecruisers were designed in the United Kingdom, as a development of the armoured cruiser, at the same time as the dreadnought succeeded the pre-dreadnought battleship. The goal of the design was to outrun any ship with similar armament, and chase down any ship with lesser armament; they were intended to hunt down slower, older armoured cruisers and destroy them with heavy gunfire while avoiding combat with the more powerful but slower battleships. However, as more and more battlecruisers were built, they were increasingly used alongside the better-protected battleships.