Restac

Restac was a Silurian and one of the Commanders in the their military. She was charged with protecting the city beneath Cwmtaff should its automated systems detect a threat. She had a xenophobic hatred for apes including humans and lust for war that bordered on psychopathy.

Biography
Her twin sister Alaya kidnapped people from Earth's surface and locked them up, presumably for experimentation. This might have been vengeance for the humans drilling (unknowingly) into their underground city. Restac was determined to start a war to reclaim the Earth from the human race. She was ordered by Malohkeh (who was also a Commander in the military, but preferred his laboratory) and Eldane (the leader of the Silurians) to put down her weapon after threatening to execute the Eleventh Doctor, Amy Pond and Nasreen Chaudhry. Instead, she went on a rampage. Restac threatened the humans and killed Malohkeh. When she learned Ambrose Northover had murdered her sister, Alaya, she began to drive the humans out, but Eldane released a deadly gas, forcing Restac's warriors to retreat to their hibernation chambers. Restac refused to leave and was killed. With her dying breath, she fired a shot at the Doctor, but Rory Williams took the blow. (TV: Cold Blood)

In 1888 A.D. she successfully hunted Jack the Ripper and comes home with her maid saying "He's here" and finds the TARDIS parked in her living room. She describes the doctor as an "old enemy" and wanted to settle everything out once and for all but the doctor must have convinced her to aid him in the future. A Good Man Goes to War (TV story)

During the Battle of the Demon's Run at the 52nd Century, she and the Silurians reappear as an ally of the doctor to save Amy Pond and her child. In here, she is seen wearing the same clothes the night in 1888 and she had her maid as a companion. In the control room she attacks the guards, and provides a distraction at the doctor by shutting the lights for a few moments, allowing the doctor to escape and find Amy Pond. She is one of the few survivors after the attack of the Headless monks to defend Melody Pond.

Personality
Restac was very aggressive and preferred to settle things by fighting instead of negotiating. She hated humans, referring to them as apes. She seemed to be a psychopath, and was even willing to kill her own kind, murdering Malokeh without hesitation or remorse.

Restac was vengeful. She tried to avenge the death of her sister Alaya and tried to shoot the Doctor even though she could have gone into hibernation to protect herself from a deadly gas that killed her.

Restac was devastated that Alaya had been killed. Although she displayed grief at the sight of her dead sister, Restac usually hid her emotions, showing no signs of concern when Alaya was taken hostage. (TV: Cold Blood)

Behind the scenes

 * The events of TV: The Big Bang, in which the Cracks in Time and their effects are undone, have led to speculation as to whether certain events depicted prior to the story, including Restac's shooting of Rory, ever happened.