It would be a crime if we didin't mention any steel monsters, fake or not, this is the KV-6, also known as KV-VI Behemoth, this is a fake tank based on a mix of a few actual WW2 Vehicles.
The main gun(s) are in the center of the enormous hull, they are 2 156mm cannons, and the turret is a bigger version of the KV-2's turret to fit it's two enormous guns, ontop of this already huge turret is a BT-7 turret that was also used during World War 2. The front and back of the vehicle also features the turrets of KV-1's with the ZIS-5 guns with a caliber of 76.2mm.
These KV-1 turrets have 20mm of steel plates as additional armor on their sides and are equiped with many more machine guns for air targets. The KV-1 Turret in the back is also equiped with Katyusha Rockets. There's a few versions of this vehicle since it was never made, but it's a sight to behold.