The Soviet KV-1 was the standard WW2 Soviet heavy tank, with tremendous armor and decent firepower.
KV-1 - Tank Encyclopedia
KV-1 Heavy Tank - Best Tank Design of Early WW2 - Real History Online
Kliment Voroshilov tank - Wikipedia
The Panzerkampfwagen VI Tiger I heavy tank (1942)
KV-4 (Object 224) Kreslavsky - Tank Encyclopedia : r/WorldofTanks
KV-220 (Object 220/T-220) - Tank Encyclopedia
Panzerkampfwagen KV-1B 756(r) (KV-1 with 7.5cm KwK 40) - Tank
KV-1s heavy tank