The Knights of Ren are fully introduced in Knights of Ren were finally given adequate attention.
With the Sith seemingly destroyed at the end of Ben Solo, now known as Kylo Ren.
With Kylo as their leader, the Knights of Ren were his personal dark side-using enforcers. Little did Kylo and his Knights know, they were all pawns of the seemingly-extinct Sith. Snoke, the First Order’s Supreme Leader and Kylo’s master, was a proxy for Darth Sidious himself. Just as Kylo filled a nearly identical role to Darth Vader in the Galactic Empire, the Knights of Ren were similar to the Imperial Inquisitors. When Kylo Ren had an epiphany and became Ben Solo once more, he fought his Knights in a six-on-one battle, which Ben won rather easily.
As shown in Star Wars: The Rise of Skywalker: The Visual Dictionary, the Knights of Ren may have existed in the Unknown Regions for centuries, where their violent escapades made them the subject of horror stories among settlers of the sector. What the book also reveals is that, aside from their former and current leaders, the Knights of Ren do not use lightsabers, but instead use fabricated scavenged weaponry. This indicates a lack of nuance in their dark side abilities, since only two Knights were able to construct lightsabers and use the ancient Sith technique of “bleeding” the Kyber crystal to give the blade its iconic red color. The Visual Dictionary also states that with more refinement, the Knights could have potentially been ideal Imperial Inquisitors. With this in mind, it’s understandable that Ben Solo, whose strength in the Force is comparable to the likes of Luke and Anakin, could overpower all of them at once.
Star Wars: The Rise of Kylo Ren delves even deeper into the Knights of Ren, particularly their ideology, original leader, training (or lack thereof), how Ben Solo changed (or was changed by) them upon becoming Kylo Ren. The Knights’ original leader, Ren, explained their philosophy succinctly. They take what they want, go where they want, kill who they want, and live as they please. They’re selfish, brutal, and unpredictable, and their connection to the dark side of the Force is the perfect fuel for this mode of thinking. When Ren and his Knights face off against Luke Skywalker himself, however, it’s clear that, while strong, their power in the Force is as crude as their philosophy. Luke likens their use of the dark side to a hammer and his mastery of the Force to a blade as he trounces all six of Ren’s followers non-lethally, prompting them to retreat. It’s no surprise that Ben Solo, whose training was far more refined than theirs, thanks to Luke and Snoke, was able to similarly rout the Knights in Star Wars: The Rise of Skywalker.
