The T-100 was a Soviet prototype heavy tank meant to replace the T-35 tank. This was one of 2 designs competing with for the contract for the next soviet heavy tank, while the other was the SMK that some of us might know. Both had the same criteria which is why they both very similar. Both the T-100 and the SMK had 3 turrets at first but after an personal request from Stalin himself they went with 2 turrets. There was also a third single turreted design being developed which ended up becoming the KV-1.

Compared to the T-35, the armor was way more potent due to lessons from the Spanish Civil war where it was proven that tanks needed good enough armour to stop shells from other tanks. Only 1 T-100 was tested during the invasion of Finland where it proved to be unsuccefull due to its aging design philosophy of having multiple turret, slow mobility and the KV-1 proving to be much better and cheaper alternative. Only 2 were made with one of them being converted into the SU-100Y

In Finland ^