Despite all the whinging from fans at anyone mentioning the possibility that Snoke might turn out to be Darth Sidious' supposedly dead master Darth Plagueis, there is a little hint in the film that the possibility is there. In Revenge Of The Sith when Palpatine is explaining the tragedy of Darth Plagueis to Anakin, a distinctive musical refrain plays in the background...And here's Snoke's theme from The Force Awakens...Surely that can't be accidental? He is a master of Death after all.