Does anyone know who the other bitcoin whales are?
Satoshi Nakamoto
Hal Finney
possibly lots of early adopters who mined or bought bitcoin like Roger Ver
but we will never know. all of these are guesses unless they provide a signed proof which nobody in his right mind would do that

Ross Ulbricht, had he not been caught. But you can add the FBI to the list of richest Bitcoin holders instead :p
This was indeed a great investment for them.
I am suprised to see, that noone posted or discussed the richlists of the bitcoin blockchain. Even though it might be easy to split the money into different addresses, one could easily check the wallets surpassing or not surpassing the amount of the Winklevoss Twins. They by the way just recently invested in the Blockstack ICO.
The blockchain richlist is a rather useless metric, unfortunately. Lots of big wallets around that simply belong to major exchanges.