They don't. Some Science Fiction writers and film producers have been of UK origin: H.G. Wells, Arthur C. Clark, Gerry Anderson, that might explain it. I think you are probably thinking of the Alien mad scientist (Exeter) from the movie "This Island Earth". It is merely a facade of culture. This is certainly not true of all media space-alien portrayals.
If the nun is British, she probably will have a British accent. If she's German, she'll probably have a German accent.
No one speaks British. They have a British accent.
Yes.
I can hear a distinct British accent when you speak.
yes, he has a british accent.
Yes, if you mean English. British does not exist. She does have a British accent also
Overall, people in Brazil do not have a British accent. The official language in Brazil is Portuguese, and thus the majority of people speak with a Portuguese accent. However, due to global influences, some Brazilians may speak English with a British accent if they have been exposed to that dialect.
No, he is Australian, so he has an Austrailian accent. He does speak French, though.
There is actually no such thing as a British accent. There is an English accent, a Scottish accent, an Irish accent, or a Welsh accent. These are generally spoken within their own countries (English in England, Scottish in Scotland, etc.). However, people all over the world may have a breed of a British accent because either they are immigrants themselves or they picked it up from their family.
There is no such thing as a 'British' accent. The accent commonly heard in Harry Potter is the ENGLISH accent. I can see no reason why anyone would stop you from auditioning for a part.
Rihanna is from Barbados and speaks with a Bajan accent, which is a variant of Caribbean English.
Most people speak with accents, and pirates are just people.