All The Star Wars Characters Kylo Ren Could Be Besides Luke
The speculation is strong with this one: Who is Kylo Ren? Aside from the fact that his (or her) name might not actually be Kylo, that this Star Wars character is a member of the Knights of Ren, and that the villain(ish) character might have some connection to the Force, everything else is shrouded in total mystery. Kylo Ren could be any number of different people under that mask, even though many fan theories have pointed towards Luke being the big baddie. If Kylo Ren isn't Luke Skywalker, who could it be?
Luke Skywalker's Kid
The Skywalker bloodline is a little shady, and when you have the Force in you, it can really go either way. Anakin goes full Sith when he let his emotions take over, and even Luke loses his will to resist anger and hate during his final battle with Emperor Palpatine and Darth Vader, which almost costs him his life. If Jedi Master Luke has a kid somewhere between Return of the Jedi and The Force Awakens, he or she would be full of the Force, and may feel more a kinship to grandpappy than dad. Is it the Skywalker destiny to put all of the Jedi in the ground, or to bring power to the Jedi Order once again?
Anakin Skywalker's Long-Lost Sibling
Little Ani Skywalker is born under very odd circumstances, and even Star Wars canon doesn't seem to be clear on where the little brat came from. Is Anakin the result of a virgin birth prompted by midichlorians, or is he a genetic experiment by Palpatine in Shmi Skywalker's Force-receptive womb? Much of Shmi's life remains undocumented, as she's little more than a displaced slave when The Phantom Menace begins, with no known parentage or husband. It's entirely possible that Anakin was not alone in the universe. After all, "there is another Skywalker," and they just might want to carry on their big brother's mission. Star Wars is all about secret siblings, y'know.
Han And Leia's Kid
There's a cross section of Star Wars nerds and hopeless romantics who are dying to know if Han and Leia ever got together. The two headstrong personalities may have had enough love to make it together in a conflicted universe, or they may have just driven one another too crazy to ever make a baby. If they did have a kid, however, they'd have Force powers through Leia's lineage, and that kid could feel a kinship with their dear old departed Darth, because the Force is weird. Most fan speculation points towards Rey being a Solo, but who's to say that there was only one? Shades of the Expanded Universe may still exist here.
Luke's Clone
Star Wars is a universe where clones are possible, and genetically engineered evil twins are a regular part of outer space life. Luke Skywalker left a midichlorian-filled hand floating out in space, which is totally the main ingredient in any recipe for a fancy new test-tube Jedi. A Luke clone actually exists in the dearly departed Expanded Universe, and he has the ridiculous name "Luuke," because that's just how words work in space (so get over it). Vader's fondest wish is to rule the galaxy with his son, so a Sith-focused Luke clone would truly be filling that gap for Vader and the Sith alike.
Poe Dameron
There's some funky mind-stuff going on between Kylo Ren and space ace Poe Dameron in some of the Force Awakens trailers...at least as far as fancy editing tricks want us to believe. Poe remains a mystery for now, but could Kylo Ren be some form of split personality or Force ghost which, once dormant, is now seeking to escape Dameron's heroic self? With the right training, anyone who is Force-sensitive is capable of leaving behind a shadow of themselves that can interact with the living. Maybe the Emperor hasn't really completely died after all...
A Kenobi
With all of the speculation surrounding the Skywalker bloodline, many fans have forgotten about the Force-strong Kenobi bloodline, which remains obscured in Star Wars canon. With the Expanded Universe tossed in the trash, nothing is known about the Kenobi family legacy. Old Ben's family tree may have roots and branches spreading across the known and unknown galaxy, and they'd probably be dripping with the Force. Obi-Wan and Anakin once had a very close relationship, so any progeny of Kenobi might justifiably claim a similar kinship to Vader's ideologies.
Palpatine's Progeny
The Jedi weren't allowed to marry or have kids, intergalactic nerds that they were, but the Sith had no such rules. The entire Sith Order is the product of intermarrying with the actual Sith species of aliens, so the guys from the Dark Side weren't really anyone to argue with getting hitched. Palpatine, once a Galactic Senator and secretly Darth Sidious, is already an old dude in the Prequel Trilogy. He may have had any number of kids in an effort to produce more Sith for his ever-growing army.
Jar-Jar Binks
It's said that evil never dies, and if that's true, than Jar Jar is still out there somewhere, in his nigh-immortal Gungan form, still causing chaos in the universe. It's Jar Jar's ostensibly awkward bumblings that causes much of the Empire's rise to power, and he's one of young Anakin's most dedicated friends as Anakin sets off on his adventure to become a powerful Jedi, so concluding Anakin's ultimate mission may seem obligatory to him. Fans have speculated that Jar Jar was originally going to be the Prequels' answer to Yoda, but plans shifted once the goofy character was reviled by the known universe. Maybe Jar Jar has finally found his purpose as the Knight of Ren.
A Completely New Character
With so much focus on how these new Force Awakens characters relate to the characters we already know, there aren't too many theories that some of these new guys may actually exist without ties to the old guard. Even though Expanded Universe canon is no longer valid, it incorporates cults that worships the ways of the Sith, even if those cults' members did not have Force powers. The new Knights of Ren seems to mirror this cult idea pretty closely, so what if Kylo Ren is just a really obsessive fan of Darth Vader who has manufactured an imaginary kinship with the dead Darth? That seems like the scariest possibility of all.