For some of the older Star Wars roleplayers, I'd imagine the answer is quite a bit. But I'm curious to know what outside sources everyone uses in their Star Wars games? (Yes, I know this is all called Legends now. Let's get past that for a moment!)

I personally like the idea of Mara Jade being a villain during my Empire era games. I can modify the Emperor's Hand stat block or create her as an Inquisitor (I prefer the latter, personally). However she enters narratively, I think she's a good villain to stand in for directly fighting Palpatine or Vader.

Swap the question for me. How much Canon do I use? Only items and some details, but I prefer playing with EU material.

A mix, of both Canon and EU. In about equal parts.

I threw out the entire canon

I pick and choose from the EU as suits us. Some kind people here helped me separate the wheat from the chaff when I first arrived here.

I prefer Disney's canon, but I regularly mine Legends for ideas for planets, events, and some individuals. Thrawn will probably show up in one of my games at some point.

In stuff I run, EU is what I know, so it's what I use. There are segments of it people don't like, that I don't even like, and I sometimes steer clear of them, but it was so much material I took the time to get to know, and a lot I liked, so I can't just toss it aside, especially for Ep 7 material that is muchly Ep 4, again, surrounded my material that, typical of early stuff, in a trilogy, they haven't fleshed out WHAT THE HECK yet. Also, when their material doesn't blatantly cancel that something prior could've happened, I can use both.

If there was more about the newer stuff that I knew; who is this First Order, that acts like they are in charge, calling people "traitors", like they were betrayed, when they are a-holes, and last we saw, the Rebellion had won, and the intervening years got burned by Darth Disney? What battles toppled all those walkers? What actually took down Star Destroyers, and left them ruins on any world (I've watched, and played, lots of Star Wars, and I've never seen one go down in conventional battle)? Who are Rey's parents? Who is the old man on Jakku (Lor San Tekka), and why does he even matter, for the few minutes he seems rather cool (supported by a lot of internet stuff, and the book), just to cut down like any non Force-user, facing one in a Star Wars movie? Why does Luke hide for so long? Is he aware of just how screwed everyone is? Even with threat to his life, he hides? For having so much material I knew (before they burned it), it's irritating, to me, to now have so much Star Wars material that I don't know, or don't have answers to. The other movies will clear it up, sure, but they haven't happened, yet, and do a pretty good job, still, of not slipping out details. I find it easier to fall back on the EU stuff I DO know, and sometimes my friends DON'T, so they will be surprised, too.

Sometimes, I also use the EU instead of the canon. I am old enough, with Star Wars, to have at least partial memories of how lots of things used to be. Some of it may be my interpretation, or misinformation, from other sources, and some of it can be hard to corroborate, today, with wikis, and such, getting all cleaned up, to remain current. Back in the 90's, the Clone Wars were VERY different (no droids, for one; both armies were clones, and the Clone Masters were a thing), Darth Vader's backstory was somewhat different (his wife, not Padme, either, was pushed down some stairs, lived, and passed away on Alderaan, a few years later. This is how Leia remembers her mother), The plans for the Death Star II were a trap, arranged by Vader, the Big E, and Prince Xizor, found by the Rebels, aboard the Suprosa (Shadows of the Empire). Boba Fett's backstory was entirely different (and that schmuck, cash grab, knock off, in Ep 2, didn't even exist), Obi-Wan WAS trained by Yoda, instead of several steps separated (though I do like Qui-Gon, and Dooku, so they can stay), and Owen Lars was HIS brother, I believe (or bad sentence structure in several books I have). He also never thought of leaving the Order for a woman; more dedication than that, and on it can sometimes go. Of course, I DO inform people about all of this, if it is pertinent, at the start of the game; sort of where other GM's describe the unique world they made, for their players to troll run around in. I acknowledge that so much Star Wars material came from additional sources, and not the original writer, and that made them sometimes terrible, sometimes conflicting, and such, but as I said, it's what i know, or at least think I know, so it's what I try to use.

My hierarchy is thusly:

1) Do I like it?

2) Do I remember it?

Which pretty much means my cannon pretty much begins and ends with the six movies, the 107 Marvel Comics from the eighties, the three Han Solo books by Brian Daley, and the Star Wars Holiday Special.

I use the original trilogy, and cherry-pick EU stuff. I really don't use the prequels, but I really like the bit from the Thrawn trilogy about why the Empire stopped using clones. You know, accelerated growth screwing up a living creature's connection to the Force, making them go crazy after a while? One of my first characters was a clone Mercenary Soldier with an addiction to... was it Glitterstim? Whichever spice suppresses one's Force. Not that he had any idea what caused it, but the Spice helped prevent the nightmares and hallucinations he would otherwise get.

We use only canon material. I will make exceptions on occasion though. For example, I need to pull my Jedi Master out of one of my campaigns as she is too powerful and the pcs cling to her for protection. So I am having EU Legacy Aurra Sing come to collect a death bounty on her. Aurra doesn't get to kill her, but she really messes my character up so she has to go into hiding for a few years.

After I learned to accept that my old beloved EU was no more, I rewrote my old (more like ancient) D20 characters into new canon. So my Nightsister who was a former padawan in the new Jedi order is now a former trainee of Luke's before she helped Kylo Ren murder everyone.

All of it and none of it. It really comes down to the game. Same goes for canon. How much of it gets used really comes down to what is going on in the game.

I'm running two groups of 6-PCs in a campaign set in the Legacy-era (Imperial Knights, Empire-in-Exile, Sith Empire, Galactic Alliance Remant, Genocide of Mon Cala).

So..."lots".

My hierarchy is thusly:

1) Do I like it?

2) Do I remember it?

Which pretty much means my cannon pretty much begins and ends with the six movies, the 107 Marvel Comics from the eighties, the three Han Solo books by Brian Daley, and the Star Wars Holiday Special.

Pretty much this. I don't really read a lot of the EU, as I found most of what I did read fairly terrible. I pick and choose elements for my own campaign, and to hell with the rest. Like the idea of Sith ghosts, which is apparently not canon now, according to the FFG books. And while I like this setup, that the Dark Side is not a route to immortaility, it is in direct contradiction to the core element of plot, so I have to ignore it basically.

Beyond that specific thing, whatever works and I remember.

My guys are currently on Oricon from SWTOR so yeh I use Expanded as much as possible as it is what I grew up with and know the best. I haven't got anything against the new canon but I will admit that I was overjoyed when Nexus of Power referred to Tython as the origin of the Jedi.

I use basically all of the EU excepting the Ones, and Aboleth. Those simply don't exist in my universe, and the same with their Mortis monolith. I also didn't see either Rebels, or the new Clone Wars, so they aren't included (though I don't mind them existing.)

I use canon then cherry pick what I want from EU. That doesn't mean that EU is rare in my campaigns, I just prefer to not dump it all in the sandbox but choose the parts I like when it comes up. I also am known to change parts of EU to my liking. So EU has become a large bucket of ready made source material that I use or don't use and sometimes twist to my liking.

I kind of use my own mix.

I keep the cannon in the background for major events (Separatist uprising, fall of the Republic, destruction of Alderaan etc) but outside that I pinch a few ideas for the EU occasionally but mostly I create my own.

About the only thing I do use is information on planets and their inhabitants whichb i either grab from the books or a mix of cannon and EU.

Bits and pieces.

There's a lot of the EU that I'm happy to ignore for my games, as it gives me a greater sense of control over what's going on in the galaxy. Though to be honest, outside of the movies there's a fair bit of the new canon that I ignore as well for my Rebellion Era games, which to be fair is easy as a lot of what I don't include focuses on the Heroes of Yavin.

My current campaign is technically all expanded universe, but it's also all minor stuff that is technically also compatible with new canon since none of it conflicts or references either the EU or canon...

Really from an RPG perspective the EU only affects campaigns that are set directly in and around the characters and stories of the EU. That really only leaves a few rather specific campaign concepts...

My campaign is taking place 300+ years after the events of the movies, and a new Emperor has risen and is working on restoring the Star Forge. I also constantly look at EU for planet ideas.