Here's a
cover story from Entertainment Weekly from 2012.
"How do you know when a TV show has become a cult phenomenon? When its (often comparatively small) ratings are eclipsed by the wild ardor of its fans. Take the case of the British science fiction show
Doctor Who, whose current lead, Matt Smith, is this week’s cover star. The now 49-year-old
Who is hugely popular in its homeland but has always enjoyed a more select appeal here — not that you know that from the devotion of U.S.-based “Whovians.” "
If you look up "cult TV show" in the dictionary, there will be a picture of Dr. Who. It's bigger cult than some. But it's still a cult and likely always will be.