The television series Game of Thrones is far more popular in the US than in Britain (it is shown on a pay-tv channel in the UK). The series is based on the books of an American, George RR Martin. The accents, though, are all British - and regional British at that, which I found out when I read this BBC article today.
In the BBC piece, American TV critic Matt Zoller says that the British accent is the usual accent used in sci-fi and fantasy films, as well as films set in ancient Greece and Rome. "A British accent is sufficiently exotic to transport the viewer to a different reality," claims Zoller. The only American actor to play a leading part, Peter Dinklage, puts on a British accent in the role. The series is based on north/south conflict and the characters in the series from the north of the realm use northern English accents (Sean Bean and Mark Addy speak with a Yorkshire accent, for example).
For the full BBC article, click here.