Force lightning was a well known Force ability, most often used by practitioners of the dark side of the Force, especially the Sith. The ability was commonly referred to as Sith lightning, because of the usual users.

Force lightning was a purely offensive, energy-based attack that channelled Force energy down the user's limbs, hurling arcing bolts of electricity from the wielder's fingertips or palms; Force lightning could be executed with either one or two hands. Powerful discharges would branch out into dozens of smaller forks; thus, skilled practitioners could target several foes at once. The intensity varied based on a number of factors. A skilled user could render a target unconscious with only a short burst. A single, powerful blast was sufficient to kill a person instantly. Darth Bane's lightning, for example, would often electrocute his opponents to death on contact. Galen Marek was another Force-user who could channel lightning that would kill on contact. Both Kyle Katarn and Darth Sidious could conjure lightning so powerful that not only would it instantly kill its target, it would also physically hurl them backwards. The latter's usage was also powerful enough to render anyone caught in it into charred husks if used to its full potency, as demonstrated by his execution of Headmaster Gentis for his military coup against him.

The fact that it caused not only severe physical damage but also unbearable agony to the victim led to it being widely used as a form of torture. At the Battle of Endor, Palpatine repeatedly assaulted Luke Skywalker with lightning, and Darth Malak used it upon Bastila Shan, having captured her onboard the Leviathan and having brought her to Lehon, where he converted her to the dark side.

Depending on the level of intensity, Force lightning could ground itself on an ignited lightsaber, with no apparent ill effect on the lightsaber's operation. Darth Sidious, on the other hand, produced a blast of Force lightning that shot Yoda's still ignited lightsaber off his hand. Powerful light-siders were sometimes able to resist the attack, or even block the lightning completely. Mace Windu, with his lightsaber combat form Vaapad, could reflect the lightning back to its source with a "superconducting loop". It required tremendous effort on the reflector's part, however, as seen in Windu's battle with Palpatine; Windu was seemingly able to overcome Palpatine's lightning. Obi-Wan Kenobi was also able to deflect Count Dooku's lightning, with his lightsaber, without exerting much effort as well. Galen Marek was capable of creating a shield out of his lightning, and could deflect even Palpatine's Force lightning back at him.