Darth Vader's infamous red lightsaber has taken many lives within the Star Wars universe, including that of his former master Obi-Wan Kenobi, but where did it come from? Following the release of Star Wars: The Force Awakens, and in the lead-up to Darth Vader's big screen return in Rogue One: A Star Wars Story, a new series of canon comics titled Darth Vader: Dark Lord of the Sith detailed his early days as the cyborg supervillain - including the creation of his red lightsaber.
The Darth Vader comics also delved into the lore of lightsabers, detailing exactly how kyber crystals - the Force-sensitive crystals used to create the blade of a lightsaber - are made to turn red. In Emperor Palpatine's words, the crystals are made to "bleed" by a Sith using the Force to pour all of their pain, rage, and hatred into them, turning the blade into an extension of the user's own dark heart.
With his former lightsaber having been lost in the battle with Obi-Wan Kenobi on Mustafar, Darth Vader is ordered by Palpatine to acquire a new one - not an easy task, since the Jedi have been purged and their lightsabers have been destroyed. In order to find an intact lightsaber, Darth Vader sought out a Jedi Master called Kirak Infil'a, who had taken a Barash vow. This form of penitence separates a Jedi from the rest of the Order, meaning that Infil'a had escaped the Jedi purge. Unfortunately, he did not survive Darth Vader.
The Kyber Crystal
Darth Vader actually had two red lightsabers, though they both used the same kyber crystal. The first belonged to Kirak Infil'a, and Darth Vader took it from him during a battle on Infil'a's home planet. Vader was almost destroyed in the battle, but pieced himself back together using parts from a droid and returned to kill Infil'a, taking his lightsaber, snapping his neck with the Force, and drowning everyone in a nearby town for good measure. Vader then brought the lightsaber to Mustafar, where he could draw on the dark Force energy beneath the surface of the planet, and removed the kyber crystal from the hilt. The crystal resisted Vader's initial attempt to make it bleed, showing him visions of a path where he turned away from the dark side and used the lightsaber to kill Palpatine. Vader fought this future, however, and was finally able to pour all of his pain into the crystal, turning it red.
The Hilt
Darth Vader used Kirak Infil'a's lightsaber in a number of early battles, as he led the newly-established Inquisitorius track down and destroy the remaining Jedi. While on one such mission, Vader was attacked by mercenaries who had taken a contract to kill him. The assassins used a handheld tractor beam to pull the lightsaber away from him, but Vader used the Force to keep his grip on the kyber crystal inside. The struggle ended up shattering the hilt of the lightsaber. After dealing with the assassins, Vader built himself a new hilt of his own design and returned to Palpatine. His master was pleased by the new weapon, telling Vader that Infil'a's hilt hadn't suited him.
With his new lightsaber, Darth Vader went on to become one of the most feared Sith in history. His weapon was eventually lost when his son, Luke Skywalker, cut off his hand in Star Wars: Return of the Jedi. The hand and the lightsaber fell down a shaft into the Second Death Star's reactor core, where they were shortly followed by Emperor Palpatine himself. Rather fittingly, Palpatine and the lightsaber fueled by Darth Vader's rage ultimately ended up sharing the same grave.