Nope that one is the Ratte. There was a p-1500 on the design board called the Monster.
The Mouse was the Panzer VIII, it was still a big tank and weighed in at 188 tonnes as opposed to the 1000 and 1500 ton tanks above. The VIII got to a V2 prototype stage
On and the P-1500 which was more of a Artillary platform
