Doctor

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

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

Fiction

Doctor appeared exclusively in the UK portion of the Marvel Comics continuity.

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

Vector Prime theorized that the Doctor hailed from the Omniverse and occasionally visits the Transformers multiverse. Ask Vector Prime

Memo had a couple of posters of the fourth incarnation of the Doctor in his room. Bumblebee

"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, once in Death's Head's own comic (where DWM character Keepsake made a separate appearance), and a fourth time in the The Incomplete Death's Head miniseries. The first of these follows on from "The Legacy of Unicron!", with Death's Head careening from the Transformers' 2008 right into the TARDIS. 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 portrayal of the Tenth Doctor.
Skids's holomatter avatar in More than Meets the Eye #13 was based on Matt Smith's Eleventh Doctor. Later, in More than Meets the Eye #43 it resembled Christopher Eccleston's earlier Ninth Doctor.
The last Ask Vector Prime entry on Facebook showed Vector Prime's holomatter avatar resembled Jon Pertwee's Third Doctor.
The My Little Pony character Doctor Hooves is heavily inspired by the Doctor (Fourth, Tenth, and Eleventh amalgamated).