De Maggio

De Maggio was an officer in Bywater's security detail in the Vault, in Henry van Statten's underground base. She was charged with getting Rose Tyler and Adam Mitchell to safety after van Statten's captive Dalek, nicknamed "Metaltron", broke free. The Dalek slaughtered her comrades and caught up with the fleeing trio in a stairwell. At first they thought the Dalek couldn't climb after them. Then it began to elevate. De Maggio sent the youngsters on, and tried to negotiate with the Dalek, to no avail. Finally, she bravely opened fire on it in an attempt to stop it, and it exterminated her.

Biography from the TARDIS Data Core article, licensed under CC-BY-SA