Hands-down, it has to be Dick Van Dyke as Bert in Mary Poppins. As Eddie Izzard put it, "Dick Van Dyke, he went for a Cockney accent. He sounds like he went to Australia to learn it!"
More like “mockney.” Dick Van Dyke is a talented man, but I find it difficult to watch
Mary Poppins today because of that ear-grating phony accent.
Did Connery even try to affect a different accent in Marnie? With him, it's practically a running joke how every role he plays, he has a Scottish accent regardless of the character's nationality.
In
The Hunt for Red October, Connery played a Russian submarine commander with a Scottish accent!
The character was Japanese, not Chinese. It was deliberately over-the-top and certainly not intended to offend anyone. Remember, this was more than 50 years ago.
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Many of us Yanks do, in fact, refer to our country as “the States” when we’re abroad.
Vocabulary is a different matter than accent, but I’ve heard some hilarious clunkers in that area by British actors trying to sound American (and vice versa). In an episode of
Fawlty Towers, a stereotypically loud, boorish American businessman says, “I’m gonna bust your ass!” Uh . . . you can bust someone in the face or in the chops or in the kisser, but you don’t bust another person’s ass. You bust your
own ass working hard.
And someone should tell hack British screenwriters that Americans don’t use “dear” to mean expensive. And that in the U.S., collective entities like corporations, universities, and organizations take singular verbs, not plural ones.
Matt Frewer's "Australian" accent on Eureka is pretty dire.
The Sundowners (1960) is set in Australia with Australian characters — all played by English, Irish or Scottish actors. The Aussie accents range from passable to awful.
Oh yeah, I just remembered a Mission: Impossible episode, "Chico," in which Leonard Nimoy did one of the worst accents in history. As I described it in my blog review, his character Paris impersonates "a sailor whose accent wanders all over the globe between Australian, Cockney, cowboy, a bit of James Doohan Scottish at one point, and Nimoy’s own normal accent, sometimes within the course of a single sentence."
That reminds me of Barbra Streisand in
Hello, Dolly! She ranges from her Yiddish-inflected Fanny Brice in
Funny Girl, to a Mae West impersonation, to a quasi-Southern accent — sometimes all in the same scene.