One of the more interesting theories, however, is that Snoke is actually Darth Plagueis, the Dark Lord of the Sith who Palpatine speaks to Anakin about in Star Wars: The Revenge of the Sith.
Supreme Leader Snoke is not Darth Plagueis, Lucasfilm says so.
Snoke is one of the more curious characters of Star Wars: The Force Awakens, with a history as shrouded in mystery as anybody.
There are a collection of fairly entertaining, if not particularly likely, fan theories regarding Supreme Leader Snoke.