Adam Mitchell

Adam Mitchell was a young English researcher in the employ of the American GeoComTex billionaire Henry van Statten in the year 2012. He was briefly a companion to the Ninth Doctor.

Biography
Adam was a genius who had 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 recruited by Van Statten. The Ninth Doctor and Rose Tyler met Adam in his early twenties. He worked at the time in Van Statten's Vault in Utah where he catalogued extraterrestrial artefacts for his employer. When the Dalek Van Statten had "collected" got loose and went on a rampage, Adam found himself running from it with Rose. He told Rose that he had always wanted to see the stars; she asked the Doctor to take Adam along with them in the TARDIS. Rose also found Adam attractive. Despite the Doctor's skepticism about Adam as a potential fellow traveller, he agreed. (DW: 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 and greed. Desperate to gain all the information that the Fourth Great and Bountiful Human Empire had collected, he learned that only those with an implant could access the data. He had a top-of-the-line computer interface port known as an infospike installed in his head. Unfortunately for 21st century sensibilities, when the implant activated, his head opened up, revealing part of his brain. The implant was activated by a snap of the fingers, so he could access the future's computer systems. He attempted to transmit information back to 21st century Earth using Rose's "superphone". (Along with the interface port he also received the Vomit-O-Matic for free.)

When Adam tapped into the computer systems, he inadvertently gave the Mighty Jagrafess of the Holy Hadrojassic Maxarodenfoe knowledge of - and nearly access to - the TARDIS. Learning of this and his additional breach of trust, the Doctor angrily returned Adam to his home, despite Adam's apologetic pleading. The Doctor then destroyed the answering machine which had received the information from the future. He 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 find out where it came from. After the Doctor and Rose departed, Adam was met by his mother who, when talking to him, clicked her fingers. As his head opened up, a look of shock and horror appeared on her face. (DW: The Long Game)

Behind the scenes

 * The "disregarded companion", Adam Mitchell, is the only companion from the revived series not included in DW: Journey's End, the finale to Series 4 of Doctor Who, nor the Doctor's "farewell tour" of DW: The End of Time (although the Eleventh Doctor later claimed in SJA: Death of the Doctor that he visited all of his past companions prior to his regeneration). Adam is also the only known companion of the Ninth Doctor not also to be a companion of the Tenth Doctor. He is also the only companion to be kicked off the TARDIS just one episode after joining the Doctor. Adam is the only known companion to be actually expelled from the TARDIS crew due to bad behaviour.
 * 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" focused 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 later.
 * Adam is a member of a small group of companions who had no scenes in the TARDIS interior. He is seen entering and emerging from the TARDIS several times, but he is never seen within the TARDIS itself.