Force lightning, also known as Sith lightning, was a power that Force users could conjure through the dark side of the Force.
Force lightning first appeared the canon continuity in the 1983 film Star Wars: Episode VI Return of the Jedi, the final installment of the Star Wars original trilogy. In Legends, conversely, Splinter of the Mind’s Eye is the first work this power is introduced in.
As sound designer Ben Burtt wanted sounds for sparks and artificial lightning akin to those in Frankenstein films during the production of the 1977 film Star Wars: Episode IV A New Hope, Burtt tracked down Ken Strickfaden, the person who built and kept the props of Frankenstein, and asked if he could record sounds from the still-functional Frankenstein props. Strickfaden initially denied the request, but, during the production of the 1980 film Star Wars: Episode V The Empire Strikes Back, was stunned after watching the 1977 Star Wars film and drove Burtt to his house in Santa Monica, switching on 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 made use of sounds recorded from Strickfaden’s Frankenstein props, with the sound effects being used in subsequent Star Wars media.
There has been a debate about the consequences of Force lightning in an individual. In Revenge of the Sith, after having been bested 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, previous to the Force lightning’s appearance in Sith, Sidious blasted Luke Skywalker with Force lightning in Return of the Jedi several times and Skywalker wasn’t disfigured or scarred. Likewise, Dooku used this power on Anakin Skywalker without permanently damaging him. Though an official explanation of this inconsistency has yet to be given, Lucasfilm Story Group‘s Matt Martin has shared his thinking for what the explanation could be, as he never saw it as an inconsistency. In his mind, it was Sidious’ own fault that his disfigurement took place, assuming that he overexerted himself, causing the Force lightning’s voltage to be higher, unlike when he later attacked Skywalker.