Judd’s Theory
Luke is Snoke. He started off as a method of bringing out what was left of the Imperial machine but the power has corrupted him. He has a holographic communicator in his hideaway. He was looking for a great Sith evil that he felt in the Force. The anger and corruption he was noticing was himself.
Jim’s Amazing Theory
Leia is Snoke.
She was being marginalized in the New Republic government, like Churchhill after WW2. This doesn’t sit well with her, and leads to her fall to the dark side. She masters it, creates the Snoke persona — who only communicates by hologram, or through completely dominated underlings — and starts the First Order, using some of the Imperial Remnant and deliberately aping the Empire to create a recognizable boogeyman.
She needs a Vader to her Emperor, of course, but luckily her brother has been training her son in the ways of the Force. She knows exactly how to play on Ben’s feelings of inadequacy and neglect: exacerbating them as Leia and manipulating them as Snoke. His fall in nearly inevitable, while never knowing who his new master truly is..
Leia uses these “new” threats to get money from the Republic to start the Resistance. She wages a shadow war against herself until she can use the First Order wipe out the Republic government and then the Resistance to heroically destroy the superweapon that did it, leaving herself as the obvious choice to rule the galaxy. And hey, if she gets to off her deadbeat ex along the way, all the better.
Phasma knows, that is why she turned off the shields without a fight. Captain Phasma was the deeply embedded double-agent there to make sure the Starkiller didn’t kill Leia, the soon to be Empress of the Galaxy.
The reveal in Episode VIII: “Kylo Ren, I am your mother.”

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“snoke, v.” OED Online. Oxford University Press, December 2015. Web. 30 December 2015.
I feel like I should complete the circle by coming up with a theory that Han is Snoke.
I’m pretty sure Snoke will turn out to actually be Gollum.