The KV-85 was the last in the KV series of heavy tanks, but in practice was little more than a stop gap variant before better designs became available. The KV-85 was based on the KV-1S with increased frontal armor and armed with a more powerful 85mm gun, as the 76.2mm of the KV-1 was now deemed unsuitable for taking on the new generation of German tanks such as the Panther. As it was developed concurrently with the IS-1, it was decided to use the latter's turret in later production vehicles, but compromises had to be made due to the larger size of the gun compared to the KV-1, notably by removing the fifth crewman. Additionally, the ball-mounted hull machine gun of the KV-1S was removed. The KV-85 saw only modest combat, mostly in 1943, but like the IS-1, was gradually phased out of service once the IS-2 was introduced in early 1944.

The KV-85 was one of the two designs by Lt-Col Kotin's design bureau to introduce a new heavy tank, the other being the K-13 prototype that led to the IS-2.