The Three Doctors (Doctor Who) the Third Doctor (Jon Pertwee) for help when Omega drains their civilisation's power. The serial opened the tenth anniversary year of the series, and features the first three Doctors all appearing in the same serial. This makes it the first "Doctor Who" story in which an earlier incarnation of the Doctor returns to the show. A superluminal signal is sent to Earth, carrying with it an energy blob that seems intent on capturing the Doctor. The homeworld of the Time Lords is also under siege, their power being drained through a black hole. Trapped themselves, and desperate to send help,
The Doctor (Doctor Who) and the junkyard in which they find him bears the sign "I.M. Foreman". When addressed by Ian with this name, the Doctor responds, "Eh? Doctor who? What's he talking about?" Later, when Ian realises that "Foreman" is not the Doctor's name, Ian asks Barbara, "Who is he? Doctor who?" In an ultimately unused idea from documents written at the programme's inception, Barbara and Ian would have subsequently referred to the Doctor as "Doctor Who", given their not knowing his name. Throughout both the classic and revived programme, a running joke is that when the Doctor is introduced as just the