Energizer Bunny

The "Energizer Bunny" was a small male lagomorph-like creature that used an Energizer battery attached to his back to keep going and going. The Sith Lord Darth Vader was sent by his master, Emperor Palpatine, to take the Energizer Bunny's battery. However, after a brief duel in Cloud City's carbon-freezing chamber, the Bunny was able to escape from Vader after the batteries in the Sith Lord's lightsaber ran out, leaving Vader disarmed.

Duel with Darth Vader
Sometime during the Galactic Civil War, the Energizer Bunny's presence in the Force was so strong that it registered on the sensors of the Star Dreadnought Executor—a remarkable occurrence, given that detecting the Force generally required very specialized equipment such as a Force detector. Despite this, it is apparent that Vader only took action with regard to this matter after Emperor Palpatine ordered Vader to "get his battery" after sensing the "great disturbance in the Force" caused by the Energizer Bunny.

Vader and the Energizer Bunny eventually met at a carbon-freezing facility at an undisclosed location, possibly Cloud City. Vader soon discovered that retrieving the Energizer Bunny's power cell would not be as easy as he had thought. He taunted the Energizer Bunny and tried to lure it to the dark side of the Force. It easily evaded the Sith Lord's attacks by spinning. Eventually Vader's lightsaber, which had been powered by allegedly inferior Supervolt power cells, died out.