Wasn't Davros a head in a jar in Revelation?
Up until the last scenes, where he getsshot in the hand. Colin's Doctor then offers to shake stumps with him. And people thought Han Solo acted like a cold blooded pimp in saying "I know."
To me, the most overarching link to the Mythos is the JFK's death forever associated with Dr. Who's birth, as Mark's "Adventure-" relates.
Ironically, one of the Star Trek Film's was to feature JFK at Dealy plaza--but that would actually work better for Doctor Who.
Even 50 years on--its too fresh...but if there is a 100th anniversary of Doctor Who and or a last episode, maybe having JFK live as the Doctor dies would finish things up somehow...