Restac

Restac was a Silurian and one of the Commanders in the their military; she was charged with being the protector of the city should the automated systems detect a threat to it. She possessed a hatred for humans and lust for war that bordered heavily 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 down (unknowingly) into their underground city. Restac was determined to start a war to reclaim the Earth from the human race. When 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, she went on a rampage. Restac threatened the humans and killed Malohkeh. When she discovered that 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. (DW: Cold Blood)

Personality
Restac was very aggressive and preferred to settle things by fighting instead of negotiating. She hated humans and called them "Apes". 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. (DW: Cold Blood)

Behind the scenes

 * The events of DW: The Big Bang, in which the Time Field is undone, have led to speculation as to whether certain events depicted prior to the story, including Restac's shooting of Rory, ever happened.