Steven Moffat's 10 Greatest Additions To Doctor Who
2. Empty Child
The first of many creepy creatures spawned from the mind of 'the Moff', the Empty Child remains one of the series' most chilling villains, despite only appearing in one two-part story. The words 'Are You My Mummy?' still strike fear into the hearts of Whovians to this day.
The creature was born from well-meaning nanogenes, misunderstanding how humans are supposed to look, and 'repairing' Jamie, a child killed in a bombing during WWII. Wearing a gas mask at the time, this is how the nanogenes thought humanity were supposed to look. Things take a further turn for the worse as the nanogenes set about 'repairing' almost everyone who is unfortunate enough to cross Jamie's path.
As with quite a few Moffat stories, a twist has Jaime's Mother, Nancy, convince the nanogenes that they have made a mistake, leading to a heartwarming ending when they restore Jaime, and everyone else, to proper human form.