At a first, hopeful glance, it seems as though this creature could be an update on the Sea Devils, a classic Who monster not seen since the days of John Pertwee's Third Doctor. However, more likely is that this is the Fisher King. No it probably won't have anything to do with the Robin Williams film, and nor does it appear to be the Wounded King from Athurian legend. Instead this version is played by former basketball player, and Britain's tallest man, the 7'7" Neil Fingleton (who has also appeared in Game of Thrones, because by this stage which actors haven't been on both shows?). The Daily Mirror first reported the story, saying that this iteration of the King would be a crashed alien that makes its home in Loch Ness. Whether the Loch Ness part is true or not remains to be seen, but it does certainly seem to have some involvement with that underwater base we saw quite a bit of in the first trailer. If it does happen to be connected to the legendary Fisher King, in some sort of roundabout way, then the question it throws up is: what's the Holy Grail that it's protecting?