Rusty (Into the Dalek)

"Rusty" was the name given by the Twelfth Doctor to a Dalek that was captured by the forces of Combined Galactic Resistance. Voicing its belief that the Daleks needed to be exterminated, "Rusty" was investigated by the Doctor, only to see if it was possible to exist a 'good Dalek'.

Rusty explained that his suppressed memory of a star being born had been triggered and seeing it caused him to realize the beauty in the universe and life. The Doctor, Clara Oswald, Journey Blue and two soldiers were shrunk and ventured into Rusty to try to fix the damage that was killing him. Using his sonic screwdriver, the Doctor repaired a crack in Rusty's power source that was leaking radiation and killing him.

However, without the radiation affecting him and restored to full power, Rusty turned evil again and went on a rampage, killing several soldiers and sending a distress call that attracted a nearby Dalek flying saucer. Upon urging from Clara, the Doctor decided to try to turn Rusty good again and had Clara reactivate his suppressed memories so he could see the birth of the star again and be reminded of the universe's beauty.

Clara succeeded and the Doctor telepathically linked with Rusty to show him more from inside his own mind. At first it seemed the Doctor had succeeded, but the beauty Rusty saw was in the destruction of the Daleks by the Meta-Crisis Tenth Doctor who he saw as evil. (TV: Journey's End)

Rusty then went on a rampage, slaughtering the Daleks attacking the Aristotle and calling for a retreat by the saucer, claiming the ship's self-destruct had been activated. Rusty left with the Daleks to continue his efforts against them, telling the Doctor that there are no good Daleks but that the Doctor would make a good one himself. (TV: Into the Dalek)