In advance of the fifth and last season of The Wire, HBO released a documentary-like special called "The Last Word". The very first line is from an interview with series protagonist Dominic West, who says: "What makes The Wire so amazing is its level of authenticity." (Watch the first part of the special here.)
Even now, after having re-watched the entire series several times, I'm floored by the irony of that line, spoken in West's native British dialect (born in Sheffield, but of Irish descent). West plays Detective James "Jimmy" McNulty of the Baltimore Police Department, and McNulty is a very American character: breaking all the rules in a very selfish (but also self-destructive) way, all in the name of some greater good (doing "real police" work and catching the bad guys). So how authentic can the show be, if this very American character is played by a Brit?
Pretty damned authentic, as it turned out. Although I understand that many folks familiar with Baltimore-area speech could somewhat reliably distinguish the Baltimore-native actors from others, there were probably very few who would have picked out West as British or even as not American (or Idris Elba for that matter, another Brit who played Russell "Stringer" Bell on the show). These folks are actors, after all — really good ones who do what it takes to play their characters as authentically as possible, speech and all.
I don't recall there being much more than benign surprise among the viewing public upon hearing these actors' real voices, though maybe I wasn't paying enough attention at the time; perhaps this is because The Wire was "just a TV show". (Putting aside the fact that writer/creator David Simon was awarded a MacArthur Grant in large part for his work on The Wire.) By contrast, some folks appear to be getting very upset that the American superheroes Batman, Spider-Man, and Superman are being played in movies (both recent and forthcoming) by British actors: Christian Bale, Andrew Garfield, and Henry Cavill, respectively. Why all the fuss?
Much of the complaining appears to center around the plain fact of nationality: these are American heroes, so they should be played by American citizens. [Concerning Superman, there's a lower-level argument among the geekier commenters: Superman isn't American, he is an alien from Krypton! say some; But he came to America as a young boy and was raised by the Kent family! say others. (The same kind of argument goes back and forth concerning Andrew Garfield: Garfield isn't British, he was born in LA! say some; But he moved to the UK as a young boy! say others.) Wow, is all I can say.] But Gretchen Carlson of Fox & Friends comes right out and says it. Speaking of the choice of Henry Cavill as Superman, she says:
So he's a good-looking chap. Now, you all know — if you watch the show — that I'm a big fan of the British accent. When [unintelligible name] comes on the show, whatever he says, I just like listening to him. But maybe not as Superman, because he's gonna probably have to get rid of the accent to be the Superman character.
I suppose I don't blame Carlson for (implicitly) worrying that Cavill might consider not "get[ting] rid of the accent"; after all, Kevin Costner was roundly criticized for not giving his Robin Hood character a British accent back in 1991 (see e.g. here). But is that really an option for Cavill? At the very least, he would be bucking the trend: Christian Bale has a very convincing American accent in the Batman movies (he even kept it on for this Fresh Air interview, in deference to the expectations for the character; listen to the last couple of minutes), and Andrew Garfield has already proven that he can play a convincing American in his role as Eduardo Saverin in The Social Network. But Carlson's concerns betray what I believe to be the driving force behind all the fuss: the belief among many Americans that British speech is an accent (one that Carlson is "a big fan of", mind you), that (standard) American speech is not, and that to be a Brit playing an American you have to "get rid of the accent". Forget the fact that this happens, like, all the time in the movies and television, in both directions — and more often than some of us may care to admit, very convincingly so.
Incidentally, Dominic West has a hypothesis as to why "British actors are getting big parts in American TV shows" (and movies): "Maybe it's because we're cheap." With regard to the superhero parts in particular, the suggestions that have been made tend to revolve around the general claim that the current crop of youngish male American actors isn't up to snuff for superhero-dom: too fat, not sufficiently manly, and so on. Whatever. I'm just looking forward to seeing even more superhero movies.