Doctor

The name or term "Doctor" refers to more than one character or idea. For a list of other meanings, see Doctor (disambiguation).

Contrary to what you might think, He should not have turned left...

Doctor is somebody from the Generation 1 continuity family.

Doctor is a being whose existence is indicated in radio wave communication. He is presumably concerned about the Daleks.

Fiction

Starscream flew over the English countryside, picking up transmissions involving, among other things, Doctor. To a Power Unknown!

"Doctor" is, of course, the Doctor, the main character of the long-running British science-fiction programme, Doctor Who. Starscream is probably picking up Revelation of the Daleks, a Colin Baker serial. But...
...the Doctor has twice encountered Death's Head in the Doctor Who Magazine comic strips, and a third time in the The Incomplete Death's Head miniseries. And there are potentially some Daleks in the Transformers universe...
Pyro Ignatius Spark's personality in Generation 2: Redux seems to be based on David Tennant's incarnation of the Doctor.
The character Natasha Pyraniac from the Animated adventure Time-Quake seems to be based on / influenced by one of the Doctor's foes, the Rani.