But beware, the data core carries information about the Doctor's deadliest enemies - and in his computerised form these "avatars" are as deadly as the real thing. Jump on them to delete them from memory.
Collect ten artron energy crystals before proceeding. Judoon troopers will try to stop you by cataloguing you as non-human.
Because of the ubiquity of this race, no attempt will be made here to list every appearance in every medium. Instead, we focus on game appearances here, and invite you to explore a complete list of appearances elsewhere.