Millie Peterson

Millie Peterson was a young girl who was the cousin of Louie Rollins. She aided the Eleventh Doctor on several occasions.

Biography
Millie's mother was Rachael Peterson, and her cousin was Louie Rollins, who was also ten years old and had only been born within a few days of her. (WC: Snowfall)

Millie and Louie had been to a fun Halloween party the night before Louie encountered the Doctor in a warehouse. After the incident, Louie, Millie, and the Doctor were enjoying Bonfire Night when the effigies of Guy Fawkes sprang to life, a result of an alien that had been staking out in the warehouse. The Doctor took Millie and Louie with him on the TARDIS to the warehouse and they refused to stay in the TARDIS while he dealt with the alien. After the alien and its equipment had been destroyed, the trio returned to Bonfire Night to enjoy toffee apples. (WC: The Night After Hallowe'en)

At Christmas, Millie called the Doctor and invited him to join she, her mother, and Louie at a pantomime of Peter Pan. Though the Doctor was busy at the time, he later remembered the call and arrived at the theatre. The theatre's power was sabotaged by a Brakari, who needed the energy for her and her baby to survive. When Louie lost heat and fell weak, Millie and the Doctor retrieved blankets for him. On the way back, Millie tripped on the icy carpet and almost fell over the balcony, but the Doctor caught her. The baby Brakari attached herself to Millie's back for energy, though the Doctor sonicked it off. She later helped the Doctor reach his TARDIS, which was residing in a deadlock sealed room, by realising that he could use the sonic screwdriver on the screws of the door's hinges. After helping the Doctor carry equipment to help the Brakari and Louie, she joined him, her mother, Louie, and Big Jack on the TARDIS to release the Brakari in space. (WC: Snowfall)

The next year, there was a snowstorm and wide-spread blackout. When Louie was visiting her, Millie got a call from the Eleventh Doctor on her mobile phone, even though the battery was dead and there was no reception. The Doctor had been pulled off-course by unknown forces and was trying to figure it out. Millie pointed out that the snow was still fluffy, even though it should have melted and refroze, allowing the Doctor to identify the phosidium in it. While the Doctor, Louie and Rachael went to the TARDIS to search for more, Millie investigated a snowman who seemed to have glowing eyes. When she touched it, it came to life and attacked her. (WC: Attack of the Snowmen)

Appearance
Millie was described as being shorter than Louie with curly black hair. (WC: The Night After Hallowe'en)