system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why does British seem to be the go-to accent for movies/TV shows with fantasy/medieval themes?
gpt
High fantasy was largely codified by J.R.R. Tolkien's books set in Middle Earth. Much of the feel of it was set in a kind of medieval England or medieval Europe, and it borrows liberally from English and European folklore in that regard.

So: why are medieval themed pieces using British accents? Well, simply put, the medieval times ended in the 15th Century, but the USA wasn't colonised until the 16th/17th centuries. From a historical perspective, "medieval America" didn't exist, and so fantasy or medieval themed shows using English accents makes sense: it helps place the show in England.