Force lightning, also called Sith lightning or dark rays, represented an aggressive ability that Force-sensitive individuals could manifest using the dark side of the Force.
Force lightning functioned as a dark side technique that combined different elements. It involved releasing electrical energy from the user's hands and had the potential to kill or cause intense suffering to the target. It could also lead to disfigurement or even disintegration. Additionally, it could be employed to obliterate physical objects, such as starships. Furthermore, the user's hand might emit slight traces of smoke immediately after using this power. Occasionally, this power served to counter another's use of the Force. Stunning an opponent with this power was achievable, as was manipulating a target using the lightning.
Luke Skywalker viewed it as the ultimate physical representation of the Force. The Baran Do Sages understood a method for employing Force lightning without relying on the dark side. In certain instances, the intensity of Force lightning reached such heights that the victim's skeleton became visible through their skin—as seen with Windu—or even through heavy armor. During the mission to Pasaana, while engaged in combat with Kylo Ren, the Jedi Rey unleashed a surge of Force lightning so potent that it annihilated a First Order troop transport ship. Shortly thereafter, during the Battle of Exegol, Darth Sidious, having assimilated the power of a dyad, unleashed a tempest of Force lightning with such power and precision that it completely incapacitated an entire fleet of 14,000 ships, while sparing his own fleet of Xyston-class Star Destroyers.
One variation of the ability, known as chain lightning, involved a lightning burst that spread from the initial target to surrounding individuals. Sometimes, this power manifested as a wave of stunning sparks. Another variant, employed by Sidious, was the power Dark Aura, a small-scale storm of malevolent Force energy and lightning encircling its user, inflicting torture and hindering the movement of anyone within its range.
Force lightning manifested in at least six different colors: blue, green, yellow, white, and red. The typical form was a bluish-purple or bluish-white version, as demonstrated by Darth Sidious, Darth Tyranus, Snoke, Yoda, and Rey. Nightsister magick equivalents were green, resembling magical ichor, as shown by Mother Talzin. Darth Momin's lightning glowed yellow, and red lightning was used by the Son—a representation of the dark side—and the disembodied spirit of Darth Vader when he entered a portal in his castle on Mustafar.
Jedi and Sith possessed the ability to deflect lightning using a lightsaber, as demonstrated when Obi-Wan Kenobi blocked Dooku's lightning with his saber. A powerful Jedi Master like Yoda could deflect the attack using Force deflection, but only for a brief period and with significant effort. Gungan personal energy shields were also capable of repelling Force lightning, as were Squad shields. Mace Windu and Rey both managed to redirect Sidious' lightning back at him using lightsabers. In Rey's case, the force of his own reflected lightning ultimately led to Sidious' destruction. Anakin and Obi-Wan could use their lightsabers to absorb Dooku's Force Lightning. Quinlan Vos successfully deflected Tyranus' Force lightning back at him with his lightsaber. Despite the defensive capabilities of a saber, a sufficiently fast lightning bolt could potentially disarm a lightsaber wielder.
Quinlan Vos described the sensation of being struck by Dooku's lightning as both burning and freezing his limbs. Individuals harmed by Force lightning often writhed in pain, experiencing uncontrollable muscle spasms. After Asajj Ventress was struck by Dooku's lightning, her skin developed dark lines where the bolts had impacted. One dark sculpture owned by Sidious had the ability to ground Force lightning, preventing damage to his public office when he lost his temper.
Beyond its obvious applications for stunning or eliminating enemies, this power served other purposes. Momin intended to infuse his engine with the Force through his version of Force lightning at the moment of ignition, aiming to slow down time and permanently capture the expressions of horror and pain on the city's inhabitants. Count Dooku employed this power to torment Savage Opress, hoping to encourage him to fully embrace his hatred and deepen his connection to the Force. While traversing an illusion-filled plane of reality, the soul of Darth Vader utilized red Force lightning, blasting an illusion of his Sith Master, Darth Sidious, before confronting the apparition of his deceased wife, Padmé Amidala.
Other dark side users, besides the Sith, could also wield this ability. Mother Talzin generated her own version of Force lightning, powerful enough to block Sidious' lightning. The Son employed red lightning to attack his sister. Supreme Leader Snoke used it to subdue his apprentice, Kylo Ren, when the young knight lost control of his anger. Snoke's application of Force lightning differed from previous practitioners, as he projected energy against the ship's floor, causing it to bounce upward and knock the target off his feet. Bendu created and merged with a massive storm, unleashing lightning upon both the Imperial and Rebellion forces. Given Bendu's claims of being aligned with both the light and dark sides, the specific side of the Force he utilized in this battle remains ambiguous. Ben Solo, similarly, following a confrontation with his uncle, summoned a lightning bolt upon Luke Skywalker's Jedi temple, obliterating the structure and those inside. During his descent to the dark side, Solo also conjured lightning around himself while battling Ren. Yoda, after his death, appeared to Luke Skywalker and caused a lightning strike to burn a tree as a demonstration to Skywalker.
Although officially prohibited by the Jedi Order for most of its history, light-siders, including Jedi, could also utilize this power, and some ancient Jedi did employ it against the Sith. Dooku, during his time as a Jedi, spontaneously used it during a painful Force vision to eliminate some Presagers of Hakotei, without any known prior training. He also used it on Shenda Mol to save his Padawan Qui-Gon Jinn while on Numidian Prime, although Qui-Gon remained unaware of it. Plo Koon occasionally emitted bursts of blue sparks against his adversaries. Yoda himself conjured Force lightning while in exile on Dagobah. Yoda also possessed the ability to harness the power of absorbed lightning to temporarily amplify his telekinetic abilities. Force lightning was among the dark side powers that Luke Skywalker acknowledged might be justifiable in dire circumstances for a Jedi, though he maintained that, in most cases, using the dark side incurred a cost that outweighed any potential benefits.
During a skirmish with the First Order on a mission to Pasaana, the Jedi Rey was attempting to bring down a First Order transport she believed was carrying Chewbacca. As she and Kylo Ren simultaneously attempted to pull the transport toward themselves using the Force, her anger caused her to unintentionally unleash lightning upon it, instantly destroying the ship.
Force lightning initially appeared in canon continuity in the 1983 film Star Wars: Episode VI Return of the Jedi, the concluding installment of the Star Wars original trilogy. In Legends, the 1978 novel Splinter of the Mind's Eye marked the first instance of this power's introduction.
During the production of the 1977 film Star Wars: Episode IV A New Hope, sound designer Ben Burtt sought sounds for sparks and artificial lightning similar to those in Frankenstein films. Burtt located Ken Strickfaden, the individual responsible for building and maintaining the props from Frankenstein, and requested to record sounds from the still-functional Frankenstein props. Strickfaden initially declined the request, but after watching the 1977 Star Wars film during the production of the 1980 film Star Wars: Episode V The Empire Strikes Back, he was impressed and drove Burtt to his house in Santa Monica, activating all his props and allowing Burtt to record the sounds. Much of the Emperor's Force lightning attack on Luke Skywalker in Return of the Jedi utilized sounds recorded from Strickfaden's Frankenstein props, with these sound effects being used in subsequent Star Wars media.
George Lucas initially envisioned Force lightning as just another Force power and desired Luke Skywalker and Darth Vader to use it against each other in Empire Strikes Back. Luke would have appeared to verge on the dark side to amplify his power at Vader's encouragement, but would ultimately be defeated as in the final film. However, this idea of Luke using lightning so early in his life was ultimately not implemented in The Empire Strikes Back. The Return of the Jedi draft script featured Obi-Wan Kenobi and Yoda appearing amidst the Emperor's use of Force lightning against Luke. The two Force ghosts appeared to defend the young Jedi and deflect the Sith's attack.
A fan debate exists regarding the consequences of Force lightning on an individual. In Revenge of the Sith, after being defeated by Mace Windu, Darth Sidious uses Force lightning against the Jedi Master, who repels it with his lightsaber, deflecting it onto Sidious and disfiguring and scarring the Sith Lord's body. However, prior to the Force lightning's appearance in Sith, Sidious blasted Luke Skywalker with Force lightning multiple times in Return of the Jedi, yet Skywalker did not suffer disfigurement or scarring. Similarly, Dooku used this power on Anakin Skywalker without causing permanent damage.
While an official explanation for this inconsistency remains absent, Lucasfilm Story Group's Matt Martin has shared his personal theory, as he never considered it an inconsistency. He suggests that Sidious' disfigurement resulted from overexertion, causing the Force lightning's voltage to be higher than when he later attacked Skywalker. In Legends, it was proposed that Palpatine used a Sith power known as "Mask" to conceal his true face, implying that the lightning did not cause his disfigurement. Instead, the lightning merely shattered the alchemical disguise, revealing the Sith Lord's true appearance. Any further damage resulted from the sudden collapse of the mask due to the dark side energy blast.