When Kylo Ren (Adam Driver) made his on-screen debut in Star Wars: Episode VII - The Force Awakens, Supreme Leader Snoke (voiced by Andy Serkis) addressed him as the 'master of the Knights of Ren.' These shadowy warriors remained a mystery for 4 years until the release of Star Wars: Episode IX - The Rise of Skywalker, and subsequent tie-in material has since revealed they were established decades ago-and by some accounts, centuries ago-as a cult who worships the dark side of the Force, which they refer to as the 'Shadow'.
A Star Wars tie-in book has hinted that a fugitive Jedi may have joined up with the Knights of Ren.
