In case for some reason you've never heard that term before, your personal head cannon is different from the official cannon of the universe. It can differ in many different ways depending entirely on your personal preference.
Even before Disney bought out Lucas Films I personally have always viewed the Expanded Universe as an Alternate Universe. They may have very similar histories but there are differences that makes it impossible for everything to be connected in one universe.
To me only the original six movies have ever been considered cannon. Everything else I just ignore. There is far too much material for one person to possibly follow everything in a single expanded Star Wars universe. All that stuff is still cannon but to me it's part of an alternate universe not the one that I personally follow. Episode seven is a bit of a mixed bag. While my general rule is that the main films are part of my universe there is one character who doesn't fit into this universe. See while the expanded universe has Dark Jedi, Inquisitors, and other agents of the Dark side of the force, the movies have basically set in stone the idea that Sith is synonymous with Dark side. Every villain on the dark side has always been a Sith Lord. General Grevious is the only exception but it was explained in the movie that he can't actually use the force. He's not a force sensitive at all. He was trained to fight with lightsabers, that's it. So he doesn't even really count anyway. He's as much on the dark side as Boba Fett or Jabba the Hutt. They're evil but not actually force users.
This technically wouldn't be a problem if you don't accept the Prequels as cannon because in the original Trilogy only Vader had that title. Palpatine was only referred to as the Sith Lord Darth Sidious in the prequels. So if you pretend the prequels never happened then Kylo Ren fits in perfectly. How ever as bad as they were... especially the third one... I still accept them as cannon. Which means that there is nothing in the films allowing for any Dark Side Force users to go by a different name. They are all Sith, they've always been Sith, unless you accept the expanded universe as cannon which I don't then they must always be Sith. The name Kylo Ren and the Knights of Ren don't fit in my personal head cannon. Those names make no sense based on what I know of the original six movies.
In episode 3 Palpatine tells the story of Darth Plagueis the Wise which was actually his master before the events of the prequels. In this story he talks about Darth Plagueis trying to discover the secrets of immortality and believed him to be dead. I personally think that Snoke is Plagueis and has simply been in hiding all this time. He's obviously wounded and possibly weakened in this state which is probably why he wanted Palpatine to believe he was dead. I think that gash on Snoke's head was caused by Palpatine's light saber. Snoke is probably Plagueis' real name.
In episode 1, though they never directly stated they were the same character and in fact even toy sales at the time would have you believe they were different characters despite the fact Darth Sidious wears the same exact black cloak that Palpatine was famous for wearing in the original trilogy. This movie first introduced the idea that Palpatine also had a dual identity as Darth Sidious. This was later confirmed to be true and seriously why did they ever try to deny it? It was obvious from the start. They could of hid his identity better and made a bigger reveal at the end if they didn't use that black cloak.
Also in episode 1 we were introduced to Darth Maul who many regard as the best thing to come out of the prequels... even though he died in the first movie and didn't really do much of anything. He looked cool though. I guess he's sort of the Boba Fett of the prequels as both characters didn't really do much in the films but looked cool and had much bigger parts in the expanded universe.
Then the second movie introduced Count Dooku. Now this is a bit of an odd one as his Sith name was only spoken ONCE on screen and I find many people either didn't notice or didn't realize that they were talking about him. His name is Darth Tyranus. This was used on some of his toys including his lightsaber which was sold as "Darth Tyranus' Lightsaber" not "Count Dooku's Lightsaber". Another oddity about this character is the design of his lightsaber. Many people don't even realize this but the hint actually has two separate triggers for different functions. This was never used in the movies. Apparently in the expanded universe this was explained by saying that one trigger could be activated by his pinky to extend the blade further. This is another reason I don't accept the expanded universe as cannon. It's impossible to actually use the lightsaber as described in the EU. During production of the film his lightsaber was actually redesigned. Much of the EU material uses the original design that never actually made it into the movie but was included in promotional posters. This original design had a shorter hilt which made it possible to reach the second trigger with his pinky as described. There was only one angle bend in the hilt originally. The final design however has TWO bends and is much longer making it so that the only way you can reach the second trigger is to hold it with both hands. It's meant to be a single handed weapon so it doesn't make any sense to have both hands on the hilt. It also doesn't really make sense to have a second trigger if all it does is makes your blade longer. The placement of the trigger and the bend of the handle makes it look like a blaster. It may not be official but in my personal head cannon his lightsaber doubles as a blaster.
Then of course there's Darth Vader who was first introduced in episode 4 and revealed to be Anakin Skywalker in episode 5. If it was just him this wouldn't be an issue but those out four guys all being Sith Lords, all sharing the Darth title means that every dark side force user must be a Sith Lord and must be named Darth.
This brings us to episode 7 where our main villain doesn't fit. His expanded universe counterpart however does. In my personal head cannon every time they say Knights of Ren, I hear Sith. Every time they say Ben, I hear Jacen. Every time they say Kylo Ren I hear Darth Caedus. That's what the names should be according to the previous six movies. There should not be a Knights of Ren as there's not even an explanation for their existence or even who any of them are. There is a clear understanding of who the Sith are and who their members are. There's no reason to name him Ben because Leia knew him as Obi-Wan and Han didn't even like him so why would they name their son after him? Darth Caedus fits into the movie universe despite being first introduced in the expanded universe, Kylo Ren does not.
The general rule is that if it's in the movies it's cannon but I'm breaking that rule now. I'm also breaking the rule that every live action film is cannon because I'm not going to include the spin off films like Rouge One into my person head cannon. Just the main nine movies. Though even that is a little iffy when there are THREE DIFFERENT VERSIONS of the original trilogy.
So which version of 4, 5, and 6 do I accept as cannon... Well the VHS special edition version that was released back in the 90's. Unlike the Blu Ray version which is more recent the added special effects added to the movie rather than taking away what was already there. There was no giant CGI monster blocking entire scenes. Though Jabba the Hutt looks better in the more recent one, 90's CGI wasn't that good... He looks much more like the puppet now than he did back then. That's really the only thing in the Blu Ray that was actually improved since the 90's. Anyway for the time the 90's version did actually look much better than the original version. Everything that should be there could still be seen, everything that was added actually fit with the original movies, and all the added effects were kept to the background where they didn't block any of the main action. That's exactly how the updates should have been done. The original 70's version was great for the time but those effects got kind of dated by the time the prequels started coming out. You can't really expect that version to last forever. So basically the 90's special edition VHS version is my definitive original trilogy.
Anyway, now that that's out of the way, rather than arguing with me please remember that this is all just my personal opinion. I want you to share your own personal head cannons. No arguing what is or isn't official cannon. This is strictly an opinion based thread.
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