The IS-6, also known as Object 252, was a Soviet heavy tank developed during the final years of World War II. Designed in 1944, it was a revolutionary step in tank development, introducing advanced sloped armour that influenced the future of heavy tank design. Despite its promising features, mechanical design flaws led to the IS-4M replacing it in production. Only two prototypes of the IS-6 were ever built, both of which were scrapped at the war’s end.