Electricity

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

Electricity could also be harnessed as a weapon. Racnoss webstars could discharge electrical blasts from any of their pointed spires. (TV: The Runaway Bride)

Davros could fire electrical charges from his hand, and then later from his cybernetic arm gauntlet. These ranged from minor to fatal voltage. He could also cut out the electrical energy of all matter using his reality bomb. (TV: Revelation of the Daleks, Journey's End)

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

The Silents were also 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)

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)

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)

The newly resurrected Master was able to shoot bolts of electricity from his hands. (TV: The End of Time)

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

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

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)