Adam Mitchell, portrayed by Bruno Langley, was the Doctor’s companion for only two episodes.
In 2012, Adam was a young English researcher, employed by the American billionaire Henry van Statten. In the episode “Dalek” he was at van Statten’s base, and at the end he went with the Doctor in the TARDIS. In “The Long Game” he is travelling with the Doctor and Rose, but Adam behaves badly. At the end of the episode, the Doctor takes Adam home.