The Doctor: (After witnessing Earth's destruction, then taking Rose back to present-day Earth) My planet's gone. It's dead. It burned like the Earth. It's just rocks and dust. Before it's time.
Rose: What happened?
The Doctor: There was a war and we lost.
Rose: A war with who? What about your people?
The Doctor: I'm a Time Lord. I'm the last of the Time Lords. They're all gone. I'm the only survivor. I'm left travelling on my own because there's no one else.
Rose: There's me.