One of the most mysterious and influential characters in the new Star Wars trilogy, we first encountered Snoke in The Force Awakens, but knew little about him.
During The Force Awakens, Snoke only appeared briefly in holographic form to direct/bully his underlings: General Hux and Kylo Ren. We also learned from Leia that Snoke was the one who turned Ren towards the dark side (or at least expedited his turn). In The Last Jedi, we finally got a look at Snoke in the flesh, as it were. And it goes without saying, SPOILER ALERT!
In the lead up to The Last Jedi release, writer/director Ryan Johnson stated that we would learn as much about Snoke as we needed to for the story, but not more. He used the comparison (naturally) of the Emperor in the original movies: a mysterious, dark presence pulling the strings. As it turned out, we didn’t need to know too much about Snoke. He appeared briefly, but quickly passed on the role of major antagonist in the new trilogy.
Andy Serkis, who voices Snoke (and provides his movement) described the “supreme leader” as an individual who took the pain he felt and reflected it out across the galaxy. Someone who wanted to make others suffer as he himself had suffered. That was made very clear in The Last Jedi, as he tortured Rey when she came/was brought before him.
Kylo Ren got another chance to emulate his idol/grandfather (Darth Vader) and took it. When he was told to kill Rey in cold blood, Ren instead turned on his mentor and took him out. However, instead of using these actions to turn against the dark side as Vader did, Ren instead looked to gain power and embrace it.
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Ultimately, Snoke was a disappointment as a villain. He wasn’t very threatening in The Force Awakens, and only a bit mores in The Last Jedi. Most of that increase was (I thought) because one of the characters we were supposed to care about was threatened. We did get to see him use the Force more, and he was definitely strong, but that’s about it. Ultimately, we learned little about Snoke, because he was more of a plot device than an influential character in the story.