Adam Mitchell

Adam Mitchell was a young English researcher in the employ of American billionaire Henry van Statten in the year 2012. He is the second known companion of the Ninth Doctor.

The Doctor and Rose first met Adam in Van Statten's underground bunker in Utah, called the Vault, cataloguing extraterrestrial artifacts. Van Statten had been collecting these artifacts for years, reverse engineering them to create technologies such as broadband Internet which he then sold. Adam was also a genius, having successfully hacked into the United States Department of Defense computers when he was eight years old, nearly causing, in his own words, World War III. He was eventually recruited by Van Statten.

Van Statten had one living specimen in his museum, which he termed a "metaltron", but was actually a Dalek. The Dalek managed to break free and slaughter its way through the base, and Adam found himself running from it along with Rose. At the end of this adventure, Rose asked the Doctor to take Adam along with them in the TARDIS as Adam had told her earlier that he had always wanted to see the stars. It was implied that she also found Adam attractive. Despite the Doctor's scepticism about Adam as a potential fellow-traveller, he agreed ("Dalek").

Adam's travels with the Doctor and Rose did not last long. Visiting the year 200,000, Adam was overwhelmed by the wealth of information and technology available to him and ultimately gave in to temptation. He had an advanced computer interface port installed in his head (activated by a snap of the fingers) so he could access the future's computer systems, and attempted to transmit information back to 21st century Earth using Rose's modified mobile phone, dubbed the "Superphone" ("The Long Game").

Discovering this breach of his trust, the Doctor returned Adam to his home despite Adam's apologetic pleading, leaving there after destroying the answering machine which had received the information. The Doctor observed that Adam would have to live a quiet life from now on, lest someone discover the implant in his head and dissect him to uncover its secrets. The ease at which this could happen was demonstrated when Adam's mother returned home and snapped her fingers, inadvertently activating the implant. What happened to Adam next is, as yet, unchronicled.

Adam is the only known companion to be actually expelled from the TARDIS crew due to bad behaviour.

Reference on Doctor Who website
In 2005, the website "Who is Doctor Who?" announced that 14 year old Adam Mitchell had won a competition arranged by Van Statten the previous week. Adam's winning essay on "Why I Want To Meet An Alien" focuses on acquiring advanced knowledge from them ("I don't think it's cheating, really. It's just a shortcut"), foreshadowing both his work for Van Statten and his actions in the 2001st century. The canonicity of the material on the website is unclear.