@FD:
No time era, whoever you wish from that nation, so long as they're not "obscure," we'll say (I mean, for England, it doesn't have to be Shakespeare or Dickens or Hamlet or Oliver Twist...but picking someone who wrote one book three hundred years ago and has never been discussed since or so is just absurd, ruins the fun of recognizability.)
obiwanobiwan
Your Humble Narrator
Fortress Door
stranger
4 down, 3 to go...since we're masquerading as people, maybe we can shoot for a Halloween start date?
@stranger:
I'd think so...for instance, T.S. Eliot immigrated from the US to the UK, but he undoubtedly counts as an English poet...we'd probably officially split the credit and call him an Anglo-American or Trans-Atlantic poet in class, and he'd fit in both the US and UK canons, but for our purposes, he'd definitely count as an English poet...
So I think so long as they live a SIGNIFICANT amount of time (that is, not just a few years, it has to be a sizable chunk of their writing life) in a country as an immigrant, they can count for that country.