The Grimminy-Grew

 was a creature that liked hunting humans. It spoke in rhymes and didn't like the Ninth Doctor's interference. The people it captured thought that they were alone. Once the Doctor and Saffron Windrose got his captured people to remember their names he came after them. It had been on Earth for nearly two hundred years after falling their during the station's construction. The Doctor realised that it was the child of an older enemy of the Time Lords. He challenged it to a thought battle to guess each others true name. (AUDIO: Station to Station)