One of the stranger of the scant plot details of The Force Awakens we know was the reveal of the Knight of Ren, a cult that J.J. Abrams says Kylo is a member of (and the origin of his surname). I've not fully bought into this idea - if there is some direct misleading to add extra mystery to the pre-release hype and get fans theorising in the wrong direction, this is it. They'll be in the film in some form (they appear in the trailer), but I see it more as support than equals. Their appearance in the final trailer actually backs this up somewhat; they certainly don't seen quite as many had imagined. Many have assumed they are a cult of Dark Jedi, a less all-out evil version of the Sith, but if you look at the other Knights (again presuming) they're armed with standard blasters or physical sticks (yeah, really), implying a lack of Force proficiency to wield a lightsaber. These are probably Kylo's personal troops, given his name in some self-aggrandising manner (similar how the 501st Legion was known as Vader's Fist). Although given how they seem to come from a part of the movie we know nothing about, it could be something much, much more exciting.