Melody Pond (Prequel to The Impossible Astronaut)

This girl contacted Richard Nixon for assistance, but he did not know who was calling him. She told him about the "Monsters", and how she feared them. She told Nixon the words "Jefferson Adams Hamilton", leading Nixon to believe she was a boy, but the Eleventh Doctor helped them to discover that these were the names of street names, the only three in the same place together in Florida, and probably all of America, according street names and the only place these were together was Florida. (DW: The Impossible Astronaut)

She encountered Amy Pond who fired a gun at her. She survived and again met Amy at a children's home. The girl managed to break free of the astronaut suit that acted as life support. Her deteriorating health caused her to regenerate. (DW: Day of the Moon)