Electricity

Electricity was a form of energy. In its most useful form, electricity was what many species across the universe used for power.

Uses
Some species like the Wire could physically transform themselves into electricity and travel across galaxies in that form. (TV: The Idiot's Lantern)

The Wirrn were susceptible to electricity. The Fourth Doctor rigged up power from a transport ship to Nerva Beacon in order to create an electrically charged barrier around the cryogenic chamber. (TV: The Ark in Space)

Sarah Jane Smith destroyed a Kraal android by using electricity. She poured water on the ground, which acted as a conductor, and, when the android entered the puddle, applied the charge. (TV: The Android Invasion)

The Swarm infected its hosts through electrical pathways. (TV: The Invisible Enemy)

Daleks used electric barriers to protect themselves from Terrorkons while storing missiles in the Lake of Mutations. (COMIC: The Terrorkon Harvest)

The Kleptons used an electrified wire fence to contain their Thain slaves in their underwater city. (COMIC: The Klepton Parasites)

Static electricity
On Skaro, the Daleks used static electricity as a power source. They could not travel beyond the metallic flooring that provided them with the electricity. (TV: The Daleks) Unlike these prototypes, the first field-tested group of Daleks created by Davros had been improved to remove this flaw. (TV: Genesis of the Daleks) Other Daleks who descended from the prototype group also outmoded this feature because of the limitations caused when disconnected from their electrical source. (TV: The Dalek Invasion of Earth)

Weaponised electricity
In the 1900s, a Rutan scout killed Ben Travers, Reuben, Henry Palmerdale, Harker, Adelaide Lessage and James Skinsale with electricity. (TV: Horror of Fang Rock)

The Silents were capable of absorbing electrical energy, and harnessing it to kill their victims. Joy was killed in this way while in the White House. (TV: The Impossible Astronaut)

The Masters of Dorada could generate electric charges through their tentacles. They would give their enslaved Doradans electric shocks if they stopped working. (PROSE: The Dream Masters)

The Chameleons had ray guns which could electrocute living beings. (TV: The Faceless Ones)

The Slitheen harnessed electricity as a weapon during their first Earth invasion. They attached electrical transmitters to name tags and used them to zap half of UNIT's alien experts. (TV: Aliens of London)

Dæmons (TV: The Dæmons) and the Rutan Host (TV: Horror of Fang Rock) used electricity as a weapon.

Racnoss webstars could discharge electrical blasts from any of their pointed spires. (TV: The Runaway Bride)

The Cybermen could electrocute victims through their arm gauntlets, harming them (TV: The Moonbase et al.) or killing them instantly. (TV: Rise of the Cybermen, The Next Doctor)

Bannakaffalatta, a cyborg, had the ability to emit a high-range electromagnetic pulse. This destroyed the Heavenly Host easily, but without immediately available medical facilities, it cost him his life. (TV: Voyage of the Damned)

Davros could fire electrical charges from his hand, and then later from his cybernetic arm gauntlet. These ranged from minor to fatal voltage. (TV: Revelation of the Daleks, Journey's End)