Ren

"Ren" was an old name that stood for the leader of the Knights of Ren. By the Imperial Era, the Knights were led by Ren, a human male who had gained a red lightsaber—known as the Ren—from an individual who held the same name. After his death, the name passed to the Jedi Ben Solo who was thereafter known as Kylo Ren.

When held by Kylo Ren, the heir to the Skywalker bloodline, the title was also known as the Master of the Knights of Ren. Kylo held the title while he was apprenticed to Supreme Leader Snoke of the First Order. After usurping control of the First Order from Snoke, Ren seized the title of Supreme Leader for himself. Although he became fond of the name in time, he confessed to himself that he, at first, would have preferred a name like "master of the dark side" or commander of the Knights of Ren to be his governmental title. Ren deployed the Knights of Ren to hunt the Jedi apprentice Rey during the final days of the First Order-Resistance War. They also served as Ren's bodyguards, accepting orders only from their master to the consternation of the Supreme Council. During the Battle of Exegol, the Knights revealed their true allegiance to the resurrected Sith Lord Darth Sidious, turning against their former master, who returned to the light side of the Force as Ben Solo. The Knights' combined effort to stop him on Exegol failed, with all six members being killed by Solo.

Text and facts from the “Ren” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.