Alan Dale, a New Zealander, has played several American characters, including a Vice-President of the United States in 24, a Director of NCIS, the patriarch of the Meade family in Ugly Betty, and the devious patriarch Caleb Nichol in The O.C.. He seems to be the guy you break out for evil American roles.
Australian Portia de Rossi uses an American accent to play Veronica on Better Off Ted, Lindsay Bluth on Arrested Development, and Nell Porter on Ally McBeal. It's almost completely convincing — the only thing she can't say is "anything". And she's been in the States for so long that Australians think her natural accent is a put-on.
British Cary Elwes has used an American accent to play Apollo 11 astronaut Michael Collins in From the Earth to the Moon, an American agent in season 9 of The X-Files. In Kiss the Girls, where he affects a passable Southern accent and switches to a more "standard" American accent when revealed as the villain, but has trouble keeping his British accent from slipping through in the process. And in season 3 of Stranger Things, he was Mayor Larry Kline.
Benny Hill tried to affect a New York accent in a few sketches playing an Archie Bunker-like character. He didn't even come close.
Hugh Laurie was already a famous actor in Britain when he hit the big time in the States playing the title character on House. Before then, the extent of his American accent usage was playing a loud, obnoxious American tycoon (with an obviously fake accent) on A Bit of Fry and Laurie. But when he auditioned for House, he did so well that not only were many people unfamiliar with his British work convinced that he was a real American, Brian Singer held him up to other producers as a shining example of a "real American actor". It also shows his acting range, shifting between the English buffoon George on Blackadder and the grumpy sarcastic American doctor House — and several times on House, when the character does a Fake Brit, Laurie just uses his "George accent" and it sounds ridiculous enough that it's a plausible imitation of a Brit by an American asshole. Since then, Laurie's standard American voice is his "House accent" (which is a moderately East Coast-ified "General America, befitting House's well-off Central Jersey setting), as seen when he hosted Saturday Night Live and played an American on Veep.
William Shatner is from Montreal and he appeared in Star Trek and Boston Legal. Captain Kirk is a Farm Boy from Riverside, Iowa, and he's born there during a time of "United Earth" where national boundaries don't exist, so it might be "natural" for him to sound Canadian in any event.
Tammin Sursok (of Australia soap opera Home and Away) was cast as Colleen Carlton on American soap opera The Young and the Restless, which launched her North American career. She has been in various movies and TV shows since then using an American accent, including as Jenna on Pretty Little Liars. Although her natural accent is Australian, the actress was actually born in South Africa.
British comedian Tracey Ullman used a number of different American accents on her various sketch shows. She commented that most British actors tend to sound very nasal when doing an American accent.
Damian Lewis' best-known roles are all American characters, including in Band of Brothers, Life, Homeland, and Billions. When he accepted his Primetime Emmy Award for Homeland, many people were shocked to hear him speak in his native accent.
British actor Ross McCall plays Americans more often than not, to the point that his natural accent is drifting more towards American (which would be the second time this happened — he was born in Scotland, but his accent turned English after moving to Kent). His accent on B.o.B was reportedly so convincing that many of his co-stars were fooled.
Toby Leonard Moore is Australian, but he lives on the East Coast, and his most notable roles have all been as New Yorkers, most notably as James Wesley in Daredevil (2015) and Bryan Connerty in Billions.
British actor Gregg Sulkin has been known to play Americans, including as Wes Fitzgerald in Pretty Little Liars. It led to a weird aversion when he auditioned for a role on Wizards of Waverly Place with an American accent, and mentioned offhandedly when it was over that he was really British — and the writers cast him and decided to make the character British anyway.
Christina Ochoa is a Spanish actress who has exclusively played American characters, and she has an excellent American accent. She even plays a US soldier in Valor.
South African-born Canadian actress Kandyse McClure has rarely played Canadians or South Africans. Most roles she's had by far have been playing Americans.
Examples listing shows
British TV detective series, such as Foyle's War and Sherlock Holmes, have a habit of casting British actors as American characters — but since not every British actor can pull off the accent, they try to disguise it by making said American characters total stereotypes of pushy and obnoxious Yanks, allowing the actor to achieve the accent by speaking five decibels louder than anyone else in the scene.
12 Monkeys: Actors Emily Hampshire (Jennifer Goines) and Demore Barnes (Sgt. Marcus Whitley) are Canadian. New Zealander Brooke Williams plays Hannah Jones.
30 Rock has an unusual variation, where British actress Emily Mortimer plays a character who was ultimately revealed to be an American posing as a Brit. Naturally, her character's "fake" British accent was completely flawless, and she only did one line with an American accent.
The 100: Eliza Taylor (Clarke) and Bob Morley (Bellamy) are Australian, while Dichen Lachman (Anya) is Nepalese-Australian; Marie Avegeropoulos (Octavia) and Devon Bostick (Jasper) are Canadian; Ricky Whittle (Lincoln) is English; and Henry Ian Cusick (Kane) is Scottish-Peruvian.
The 4400: The Canadian Chad Faust, plus Australians Jenni Baird and Jacqueline McKenzie play American characters.
In Almost Human, New Zealander Karl Urban affects a pretty good American accent. One episode has him briefly revert to his natural accent (complete with "mate"), while pretending to be a hacker.
Alphas: British actor Ryan Cartwright adopts an American accent.
Our main characters are a pair of Russian sleeper agents posing as a suburban American couple.
A twofer on Matthew Rhys, a Welshman playing a Russian pretending to be an American.
All of the various KGB handlers for the Illegals Program, and most of the deep cover agents, are all American actors playing Russians pretending to be Americans. This allows these actors to avoid having to fake Russian accents.
In Legends of Tomorrow we have Canadian Victor Garber and British Franz Drameh playing Americans Martin Stein and Jefferson Jackson, as well as Australian Dominic Purcell playing American Mick Rory. There's also German (living in the US) Falk Hentschel playing multiple reincarnations of Hawkman, several of whom are American (and all of whom sound the same, even the Ancient Egyptian one).
As Time Goes By has an arc where Lionel and Jean work on an American miniseries. The producer they associate with has an American accent that's just as bad as the miniseries.
"Yrr in the shaht!"
Baby Daddy: Jean-Luc Bilodeau is French-Canadian, and although his accent rarely gives him away, his maple leaf/fleur-de-lis tattoo on his forearm (that is never covered up) sure does.
Band of Brothers was filmed in England, and thus 80% of its cast are British. To this day, many of them are approached by fans who are shocked that they're not American. In fact, it's actually easier to list the actors that aren't Fake Americans.If you're curious Ron Livingston (Lewis Nixon), Donnie Wahlberg (Carwood Lipton), David Schwimmer (Herbert Sobel), Matthew Settle (Ronald Speirs), Neal McDonough (Buck Compton), Frank John Hughes (Bill Guarnere), Michael Cudlitz (Bull Randleman), Kirk Acevedo (Joe Toye), Scott Grimes (Don Malarkey), Richard Speight Jr. (Skip Muck), Rick Gomez (George Luz), James Madio (Frank Perconte), Eion Bailey (David Webster) and Douglas Spain (Tony Garcia) are genuine Americans. Peter Youngblood Hills, who plays Shifty Powers, is an edge case; he's South African but has American ancestry and grew up in America. Bart Ruspoli, who played Ed Tipper, is also half-American but grew up in England.
Battlestar Galactica (2003): Jamie Bamber (a native Londoner) plays Lee "Apollo" Adama with an American accent, though his character isn't identified as American since the series is set several hundred thousand years before "Britain", "America", or indeed "the English language" were things. The idea was to make the relationship with Edward James Olmos more believable, in combination with Olmos wearing blue contacts and Bamber dying his blond hair dark.
On Bionic Woman, Michelle Ryan fakes it as Jaime Sommers, but she does use her natural accent when Jaime goes undercover as a British college student. Jaime keeps the British accent when communicating with a fellow agent, who comments that he's not sure why she's still using the accent but admits he finds it sexy.
The actors who play younger versions of Nucky and his father in the season 5 flashbacks, Marc Pickering and Ian Hart respectively, are both British.
Boston Legal: In Season 4, the English actress Saffron Burrows joined the show as lawyer Lorraine Weller, with a really bad fake American accent. After a few episodes (presumably after the producers realized the tremendous mistake they had made by casting her as an American), they used a hastily concocted plot twist (she was in hiding from her past life as a high-class British madam) that enabled her to revert to her natural speech, and the horrible American accent was never heard again.
Scottish actress Laura Fraser does an impeccable American accent as Lydia Rodarte-Quayle. Even her co-stars had no idea that she is really Scottish.
Kerry Condon, who plays Mike Ehrmantraut's daughter-in-law Stacey, is Irish.
In-universe, Gus Fring speaks the majority of his English dialogue in Giancarlo Esposito's native New York accent. Gus is actually a Chilean immigrant, and slips into that accent when he's angry and/or speaking Spanish.
British Gabrielle Anwar normally does a pretty darn good job of pretending to be an Irishwoman pretending to be American. Her accent works very well. Only rarely does it slip, usually when overpronouncing arrs she'd normally leave out. But very early on, they tried having her use a straight-up Irish accent, and audiences cringed, so they had her switch In-Universe to an American accent with the reasoning that she can't "go around speaking like a bloody leprechaun" in Miami.
One episode has the New Zealander Lucy Lawless faking an American accent.
Californication has Natascha McElhone, born in London and raised in Brighton, play Hank Moody's sassy, East Coast American for-all-intents-and-purposes-wife/ex-wife/lost love.
Castle: Both Castle and Beckett's actors, Nathan Fillion and Stana Katic respectively, are Canadians; although Katic did spend some of her childhood in the U.S. and does have dual nationality, she sounds considerably less New Yorker off-camera.
The Closer has an American having to be a Fake American from elsewhere in the country: Kyra Sedgwick, a New York Blue Blood if there ever was one, uses a Georgia accent to play Brenda Johnson. It's at least good enough that you can't call it "generic Southern".
Damages: Rose Byrne (Australian) plays Ellen Parsons, a young American lawyer, with a great American accent.
The creators of Deadwood realized that they could hire foreign actors and have them play recent immigrants for historical accuracy (e.g. Polish Izabella Miko and South African Alice Krige playing transient prostitutes in the third season). In Al Swearengen's case, they weren't sure whether British Ian McShane could pull off a sufficiently convincing American accent, so they added English ancestry to his past (something untrue of the real Swearengen) to explain any slips. Paula Malcomson (Trixie) is from Northern Ireland but manages very well.
Defiance: Tony Curran (Scottish), Jaime Murray (English), Mia Kirshner (Canadian), Nicole Muñoz (also Canadian), Stephanie Leonidas (English), and Grant Bowler (New Zealand-born Australian) all play Americans with very good accents, especially Curran and Murray. At the same time, Curran and Murray's characters are Human Aliens who have adopted American English as their primary language.
Dickinson: Sue and Henry's actors are both British.
In "The Chase", the Daleks chase the First Doctor and his companions through a New York skyscraper, where a tour guide (Noo Yauwk) and a tourist (Allabayama) speak in entertainingly fake accents. William Hartnell's Old West adventure, "The Gunfighters", is full of the same.
In "The Tomb of the Cybermen", Vienna-born George Roubicek and Welshman Clive Merrison play Americans Captain Hopper and Jim Callum. Their accents are quite awful.
Milo Clancey, in "The Space Pirates", has an outrageous hillbilly accent courtesy of New Zealander Gordon Gostelow.
Bill Filer's attempt at an American accent in "The Claws of Axos" was so memorable that the character even has his own fan-produced spinoff.
"American" companion Peri Brown is played by British Nicola Bryant. Her accent was all over the map in her early episodes, but got better the longer she played the character. Bryant has confirmed in interviews that when she joined the series, an attempt was made to hide the fact she was British, to the point where she was asked to stay "in character" as an American even for TV interviews. The charade lasted only a few months before she was allowed to be a Brit again off-camera.
Yee Jee Tso, who played Chang Lee in the TV Movie, is actually Canadian.
In "Dalek", the American characters are played by Kiwi Anna-Louise Plowman, Canadian Nigel Whitney, and British Steven Beckingham. Corey Johnson (who plays Henry van Statten) was born in New Orleans, but much of his accent sounds strained and over-precise at times; it's obvious he's heavily trained and spends a lot of time in the UK.
Jack Harkness is played by Glaswegian John Barrowman, who's an odd case because he was born in the UK but spent so much time in the States that he picked up an American accent in real life (except when talking to his parents). Harkness is a Fake American In-Universe as well, being from another planet in the 51st century but posing as an American officer in World War II. He does frequently show his British assimilation by yelling "Oi!" at people.
"Rosa" has this going on both in and out of universe:
Out of universe, Rosa Parks is played by British actress Vinette Robinson, and bus driver James Blake is played by a Canadian actor. The other locals are played by either British or South African actors.
In-universe, the antagonist, time traveller Krasko, uses a British accent when speaking to the Doctor, but puts on a Southern accent when speaking to various locals.
Dichen Lachman puts on an American accent when she is Sierra (and for various imprinted identities) and uses her natural Australian accent for Sierra's true identity, Priya Tsestang.
British actor Mark Sheppard plays American FBI Agent Graham Tanaka.
Dracula features Irishman Jonathan Rhys Meyers playing Dracula with an English accent — and then he pretends to be an American businessman as well.
The Dresden Files: The TV series featured Fake AmericanPaul Blackthorne (who was born in Shropshire, England and who grew up on British military bases in Germany and in England) as the very American wizard-private investigator Harry Dresden. The show also starred Fake Brit Terrence Mann (who was born in Ashland, Kentucky and who grew up in Largo, Florida) as ghost-with-a-Teutonic-name-and-a-British-accent Hrothbert of Bainbridge. Bainbridge, by the way, is a real town in North Yorkshire.
Dr. Quinn, Medicine Woman: Jane Seymour has played many American characters, and Dr. Quinn is the most notable. It was also probably the easiest, as the role allowed her to speak with an old-world Boston accent, which is about as close to British as American accents go.
Elementary: Natalie Dormer does fake-American as Irene Adler, rather as her co-star did in Eli Stone. It turns out that she was British all along, but that's the least unsettling thing revealed about her, as she's actually Jamie Moriarty.
Eleventh Hour: Rufus Sewell seems to be doing an American Standard accent.
The Evermoor Chronicles: Main character Tara, an American teen who lives in England with her blended family (her mother married an Englishman), is played by Australian Naomi Sequiera.
Euphoria: All-American jock Nate Jacobs is played by the Australian Jacob Elordi.
Eureka: James Callis as Dr. Grant. Since Grant is also a time-traveler, he has to affect an American accent from the 1940s. The accent is really terrible, although some of that is attributable to the occasionally narmtastic lines he has to deliver.
Farscape was filmed in Australia, so naturally there were quite a few:
Claudia Black has a pretty feeble accent when she plays Crichton inhabiting Aeryn's body. Her body language, though? Pure Ben Browder.
In an episode where John and Chiana are trapped inside a video game, Claudia Black plays a princess and affects a ridiculous Southern accent (with a lisp for some reason). Since it's a fairly silly episode anyway, it's a bit more forgivable.
Gigi Edgley (who plays Chiana) drifts between an American accent and her native Australian accent, depending on the episode. Anthony Simcoe (who plays D'Argo) does a better job.
During the 20-second Farscape parody scene in the 200th episode of Stargate SG-1, Canadian Michael Shanks is similarly feeble at Crichton's distinctly Southern accent. He says seven words, which is more than enough. This may have been intentional, given the over-the-top nature of the numerous other parodies in the episode (of course, Shanks' regular character in the show is also American, but he still sounds Canadian).
In Fate: The Winx Saga, Bloom's adoptive mother Vanessa is played by Irish actress Eva Birthistle.
Fawlty Towers: In the episode "Waldorf Salad", the ugly American Mr. Hamilton is played by the Canadian actor Bruce Boa, with an audible Canadian accent.
John Mahoney, who plays Frasier's all-American dad Martin, is British, although he spent decades in the U.S. before the show.
Played with In-Universe by Daphne, a British character who can't for the life of her do a Fake American. In one episode, the only thing she can say in an American accent is "Sure". She gets better as the series goes on, but Frasier comments that her American accent is so deep that she sounds like a drag queen. Interestingly, Daphne's actress Jane Leeves is also British, but she was born in Essex and grew up in Sussex, and her character is from Manchester, so she still has to affect an accent — and doesn't do very well (not that the American audience can pick up Mancunian anyway), but the irony is that the aforementioned John Mahoney is Mancunian and could do the accent naturally.
Fringe: Set mainly in Massachusetts, it stars two Australians and a Canadian in the lead roles.
On Glee, Finn is played by Canadian Cory Monteith and Chinese-American Mike Chang is played by Chinese-Costa Rican Harry Shum Jr.
The show Good Behaviour is headlined by Michelle Dockery — English actress of Downton Abbey fame — playing an American con woman. Michelle Dockery had previously parodied this in a Funny Or Die skit where she attempts to play an American policewoman but keeps slipping back into character as Lady Mary.
Gossip Girl: Ed Westwick is a Brit who plays American Chuck Bass. Parodied early in the second season, when Chuck fakes the (very bad) English accent of the aristocrat who's romancing Blair (instead of using his own natural accent).
Hannibal: British Hugh Dancy plays Will Graham. The series also has multiple Canadian actors playing Americans. Caroline Dhavernas (Dr. Alana Bloom) gets extra credit since she grew up speaking French.
Haven has Adam Copeland, who makes no attempt to hide his Canadian accent despite playing a Maine native. Lucas Bryant does a bit better, though there is a hilarious clip in the season 4 blooper reel where he is unable to say "resources" without sounding Canadian, and gets increasingly upset with himself as he tries and fails.
Hawaii Five-0 (2010 version): Aussie Alex O'Loughlin plays Steve McGarrett. It's still kind of hard not to notice that for someone born and raised in Hawaii, McGarrett's accent sounds awfully Northeastern.
Homeland has three: Nicholas Brody is played by Damien Lewis, David Estes is played by David Harewood, and Peter Quinn is played by Rupert Friend, all of whom are British.
In John Adams, British actors Stephen Dillane, Tom Wilkinson, and Rufus Sewell play Thomas Jefferson, Benjamin Franklin, and Alexander Hamilton. But it's not an easy case, as all these men, while they were seminal American figures, were British subjects and would have spoken in an accent much closer to modern British than American.
Jonathan Creek: British Anthony Head portrayed Adam Klaus with an American accent. His replacement, Stuart Milligan, actually is American. Oddly, Adam Klaus is himself a Fake American and is really Scottish, and Milligan's American accent convincingly "slips" every once in a while.
The Kennedys are all Americans, but several were played by non-Americans, including Canadian Barry Pepper (Bobby), English Tom Wilkinson (Joe), English Diana Hardcastle (Rose), and Canadian Kristin Booth (Ethel). And the Kennedy family famously doesn't have a generic American accent but a distinct upper-class New England variety that's almost entirely associated with the family.
The Last Days Of Lehman Brothers sees James Bolam put on an atrocious "Southern" accent.
Last Resort has a fake American Naval officer, Lt. Cmdr. Sam Kendal of the USS Colorado, played by British-Canadian actor Scott Speedman.
Used In-Universe in The Librarians, where John Larroquette (American) plays Jenkins, who is, at first, assumed to be American. Then hints are dropped that he's actually mucholder than he says he is and is eventually revealed to be Sir Galahad, making him a Briton. In season 2, Moriarty picks up on the hints of his accent as part of his Sherlock Scan, which allows him to deduce his origins.
Lost: Evangeline Lilly, a Canadian, plays Kate, who is from Iowa. In an early flashback, before we knew much about her backstory, Kate mentioned being from Canada, but she turned out to be lying. Since then, Canada has become a Running Gag in that any character who mentions it is lying about something.
Manhunt: Unabomber: Curiously, both leads were played by non-Americans: Ted Kaczynski by the English Paul Bettany, and James Fitzgeral by the Australian Sam Worthington.
The Man in the High Castle features several Brits playing Americans, including Rupert Evans (Frank Frink), Rufus Sewell (Obergruppenfuhrer Smith), and Burn Gormannote A half-example; he was born in the U.S., but his parents were English and he grew up in the UK (the Marshal). Canadian actress Chelah Horsdal plays the American Helen Smith.
Ethiopian-Irish actress Ruth Negga portrays Raina, a Thai woman presumably raised in America judging by her accent.
English actress Saffron Burrows plays American agent Victoria Hand.
Nepalese-Australian actress Dichen Lachman is an odd case, as she plays the Chinese character Jiaying, who nonetheless speaks English with a distinctly American accent (possibly justified in-universe due to her husband being American, though he claims that they met when she worked as his Chinese translator due to her already perfect spoken English, so it remains something of a mystery in-story).
The spin-off series Marvel's Agent Carter has English actor Dominic Cooper in the recurring role of Howard Stark.
London-born Charlie Cox as Irish-American Matt Murdock. In fact, Cox has been doing the role and living in New York long enough that his New York accent is starting to blur with his native English accent.
Australian Toby Leonard Moore as James Wesley.
Subverted with Vanessa Marianna. Ayelet Zurer is Israeli, and while Vanessa seems like she's Italian-American and has no noticeable accent, Matt makes a remark about threatening to get her visa pulled when he visits Fisk in prison in season 2, which suggests that she's a foreigner.
Ray Nadeem is Indian-American, and is played by Jay Ali, who is British with Pakistani ancestry.
The Punisher (2017): British native Ben Barnes plays Billy Russo with a Sicilian accent, and English native Amber Rose Revah as Persian-American Dinah Madani.
M*A*S*H has an intra-American example: David Ogden Stiers, from central Illinois, plays Bostonian Major Winchester with a strong Brahmin accent. Roger Ebert, who went to high school with Stiers in Urbana, IL, once commented that he sounded "like that" even back then.
The Mentalist: Simon Baker (Australian) and Owain Yeoman (Welsh). One episode has Jane being followed by a man who claims to be a government agent, whom Jane quickly figures out to be British (the guy puts on a very House-like accent).
Monk: Canadian Jason Gray-Stanford plays Lieutenant Randy Disher, and Mark Sheppard plays one villain in a weak American accent.
Monty Python's Flying Circus is made up almost entirely of Brits, except for Terry Gilliam — but it's been joked that even he can't do an American accent from having spent so long in the UKnote He was born in Minnesota, which is a very "neutral" accent, but he's been with the Pythons since the start and went as far as to renounce his U.S. citizenship (for political reasons). Any Americans in the show are going to be hilariously fake:
In the "Marriage Counsellor" sketch, John Cleese attempts (unsuccessfully) a cowboy drawl. Interestingly, the sketch was slightly redone when included in And Now for Something Completely Different, a Compilation Movie targeted at American audiences; the cowboy accent is replaced with his "voice of God".
The "Bicycle Repairman" sketch features a couple of deliberately exaggerated American accents.
The "Attila the Hun Show" sketch is about a Hollywood producer trying to make a sitcom about a historical character, and Cleese tries an American accent to match. It's... okay — it is American, but it can't seem to decide which part of America it's from. It seems the Pythons' idea of an American accent is to emphasize the "arr"s.
The "Scott of the Antarctic" sketch also features an American film producer, this time played by Eric Idle, whose accent isn't awful but still overcorrects the "r"s. Funnily enough, it also features the main exception to the bad accents — sometimes-Python Carol Cleveland, who is half American and thus can do the accent perfectly.
Moonlight: Two of the main characters are played by Fake Americans: Alex O'Loughlin (Australian) and Sophia Myles (British). In a subversion, Shannyn Sossamon, who is American, plays a Fake American character (Coraline was born in pre-revolutionary France). In fact, most of the older vampires can be considered to be Fake American characters, especially the 700-year old Lola (played by O'Loughlin's then-girlfriend Holly Valance, also an Aussie). Josef Kostan, played as a fake American by Jason Dohring (American), was originally supposed to be played by Rade erbedija (Croatian) and would have had a thick Eastern European accent.
Motherland: Fort Salem: Most of the main cast are not actually Americans. Taylor Hickson is a Canadian. Amalia Holm is Swedish. Jessica Sutton is a South African. Lyne Renee is Belgian. Kai Bradbury's a Canadian too. Guest star Bernadette Beck is English.
Murder, She Wrote has the British actress Angela Lansbury play JB Fletcher, although she moved to the States in 1940.
Nashville has no fewer than five Fake Americans, with British Sam Palladio as Gunnar, Australian Clare Bowen as Scarlett (who notably sports the thickest Southern US accent on the show), Canadians Lennon and Maisy Stella as Maddie and Daphne Conrad, and DutchMichiel Huisman as Liam.
On New Amsterdam: Nikolaj Coster-Waldau plays John Amsterdam and has a good American accent, despite the fact that both he and (technically) his character are Fake Americans: the character was born in the Netherlands and the actor is Danish. John's partner Eva Marquez is played by a Brit, and therefore is also a Fake American.
Nip/Tuck stars Julian McMahon (who is from Australia) and Joely Richardson (from England) as Americans. In general, Richardson's American accent is much more accurate than McMahon's (except when she says the word "family").
NOS4A2: American main character Vic is played by Australian Ashleigh Cummings.
NUMB3RS: In the Season 5 finale, James Callis, a Brit, plays cult leader Mason Duryea with a believable Southern drawl.
Sarah Bolger is Irish but uses an American accent to play Princess Aurora.
Georgina Haig is Australian and likewise uses an American accent for Elsa.
Cinderella's prince Thomas (and his Storybrooke counterpart Sean) are played by Australian actor Tim Phillipps. His accent slips briefly in when he's trying to convince her not to run away, but otherwise it's spot-on.
New Zealander actor Alan Dale (mentioned above) gives King George an American accent.
Elsewhere it's averted, as many of the non-American actors use their natural accents. Rebecca Mader expected to do an American accent to play Zelena, but was told to use her own English one. Emilie de Ravin — who as noted elsewhere can do a flawless American accent — keeps her Australian voice as Belle.
Gale Gordon (Osgood Conklin) was born in the United Kingdom, only immigrating to the United States as a teenager. Gordon has a notable "transatlantic" accent, something he didn't hide when he played the pompous principal.
Jane Morgan, who plays Mrs. Davis, was born in London to Welsh parents. She moved to Boston before her first birthday.
Jesselyn Fax, who portrays Mrs. Davis' sister Angela, was Canadian.
Every season from Ninja Storm through RPM has fake Americans, once the production moved to New Zealand and hired several locals to do fake Californian accents. Not all of them could do it consistently, to the point that in Mystic Force, Richard Brancatisano's inability to do an American accent led to his character becoming Australia. Beginning with Samurai, the main cast got a lot more variety — mostly Americans, but a few Aussies, Kiwis, Britons, and Canadians (including much of the cast of SPD).
Bede Skinner (Jarrod in Jungle Fury) is probably the most obvious fake American in the series.
New Zealander James Napier's horrible and incessantly slipping accent on Dino Thunder led to a Drinking Game among the fans. It's particularly noticeable when he has to say something fast or lengthy (or both). His speech in "Wave Goodbye" goes on for so long that American and Kiwi seem to merge together into Cockney.
Across the Pacific, any American Ranger in Super Sentai is played by a Japanese actor. Battle Fever J and Zyuden Sentai Kyoryuger both featured Americans in the Pink Ranger role, and Shuriken Sentai Ninninger has an American-themed Sixth Ranger, all played by Japanese actors. Kyoryuger is especially bizarre for having an actual non-Japanese actor — in this case Canadian — but the character is said to be from Europe. It wasn't until Ninja Sentai Kakkuranger that we got a real American playing an American character, in this case the Black Ranger, and the actor's real-life struggles with Japanese as a second language were worked into the plot.
In the Someone Completely Different episode of The Prisoner (1967), Patrick McGoohan affects an American accent that even an online transcript points out as unconvincing. Oddly, McGoohan actually was born in America. His character on the 1959-60 Danger Man series, John Drake, was in theory supposed to be an American working for NATO, but he basically sounded like McGoohan.
The Cat was supposed to be portrayed as a flashy American type. Danny John-Jules had a decent accent, marked by occasional cat-like yowls, but once in a while British word usage would slip in (e.g. referring to a period as a "full-stop") — although that could be hand waved by claiming he learned English from the British English documents on board the Dwarf, he's revealed to have actually learned English by watching American movies, so who knows?
Craig Ferguson, in one of his earliest TV acting roles, played Confidence in "Confidence and Paranoia", whom Lister described as sounding like "Bing Baxter the American quiz show host". He has a pretty good smarmy quiz show host accent, which makes it more hilarious when you realize that he would move to the U.S. and host a popular late-night show where he didn't even bother to cover up his natural Scottish accent.
Robert Llewellyn plays Kryten with an American accent. Like the Cat, Kryten is technically not an American (or even human); it's mentioned that he also learned English from American movies, in his case specifically Rebel Without a Cause (his idolisation of James Dean helped him break his programming). The accent is much closer to a Canadian or northern US accent, which the creators have noted before.
In his autobiography, when describing the formation of the character, Llewellyn explictly states Kryten's accent is meant to be an exaggerated Canadian.
Roseanne: The late Irish actor Glenn Quinn portrayed for several seasons the American Mark Healy, the reviled son-in-law of the title character.
Roswell has Australian Emilie de Ravin playing Tess. Emilie's accent slipped a couple of times during her first appearance on the show but was otherwise convincing.
The Sandbaggers avoided the problem of the Fake American by having American characters Jeff Ross and Karen Milner played by American actors.
Scorpion stars Walter O'Brien (based on a real life genius), who, in the show, moved from Ireland to America as a child, when the CIA discovered him and decided to make him an ally in computer hacking. His actor Elyse Gabel is English, but his American accent is completely spot-on. It's a noteworthy example in that any Ooh, Me Accent's Slipping would be somewhat justifiable considering his character's British origin, but the American sound holds up very well, even through rushed diatribes about advanced technologies.
SCTV: One old episode featured John Candy in a parody of Midnight Cowboy with a bizarre, hooting accent that was evidently supposed to be Southern US. It was intentional though, as the character's brain-meltingly awful accent (where "y'all" came out as an awkward, howling "yole") was supposed to be Stylistic Suck. The entire effect was weirdly similar to yodelling.
Sex and the City has English-Canadian actress Kim Cattrall as New Yorker Samantha.
Shadowhunters: Jace is played by English actor Dominic Sherwood, while Valentine, Jocelyn, and Hodge are all played by Canadian actors.
Smallville contains many Canadian actors, as it is filmed in Canada, despite taking place in Kansas. Erica Durance (Lois Lane), Kristin Laura Kreuk (Lana Lang), and Aaron Ashmore (Jimmy Olsen) are all Canadians playing Kansas natives. Laura Vandervoort is another Canadian playing an American of sorts, but her character Kara is really a space alien.
On Sons of Anarchy, Charlie Hunnam from Newcastle, England, plays the American biker Jax Teller. The accent he uses is a classic example of an English person overdoing an American accent, but it works for the purpose of carrying the story. His tendency to completely overdo the accent when the character is angry leads to Large Ham moments.
For whatever reason, all of the American characters in the History Channel miniseries Sons of Liberty save for Dean Norris are played by Brits (and one Irishman, Jason O'Mara). All of them attempt generic and anachronistic American accents (and Paul Revere's actor, Michael Raymond-James, affects an anachronistic New York accent despite it taking place in Boston). Weirdly, one of the most prominent actual Englishmen in the miniseries, Thomas Gage, is played by Martin Csokas, a New Zealander. This doesn't even have the excuse that John Adams does with its characters all still being Englishmen, thanks to the cast deciding to go all-American with the accents.
Spooks has various CIA agents who generally sound half New York City, half Midwestern, and thoroughly Jerkass. The later series have some dreadful accents (so bad even British people can tell), most notably Irish-Australian actress Genevieve O'Reilly as CIA operative Sarah Caulfield.
Samantha Carter, played by English-Canadian actress Amanda Tapping. Most of the time there's no problem, but a few words in particular she pronounces in a more English or Canadian manner. We don't know where exactly the character's from, so maybe when she was a kid she lived somewhere that she would pick up a few "exotic" pronunciations? It's particularly glaring in one scene where Carter comments on Rodney's and his sister's Canadian pronunciation of "sorry", then immediately says the word with the exact same pronunciation herself.
Dr. Daniel Jackson, played by Canadian Michael Shanks. His accent is mostly fine, but every once in a while a very Canadian "sore-y" or two slips out. Particularly amusing is the one sentence he speaks while playing John Crichton in the 20-second Farscape parody in SG-1's 200th episode, where he imitates the Southern accent of his co-star Ben Browder, who played Crichton originally, and the result is less than perfect. But since it's an over-the-top parody, that's okay.
Dr. Jennifer Keller, played by Canadian Jewel Staite in Stargate Atlantis. Her accent is quite Canadian, but her character is from northern Wisconsin, where most of the locals sound "Canadian" to most Americans anyway.
Strike Back has Sullivan Stapleton, an Australian, play the allegedly American Damien Scott. For extra irony/mind screw points, his "British" counterpart Michael Stonebridge is played by American Philip Winchester.
Supergirl has the British David Harewood portray Hank Henshaw, the head of DEO. The Irish Katie McGrath plays Lena Luthor, Lex Luthor's adopted sister. Her accent slips from scene to scene, but it's said that Lena was adopted, so her actual nationality isn't stated.
That's So Raven: Dutch Anneliese Van Der Pol as Chelsea Daniels, playing an American even though she still uses her own accent.
Thunderbirds: Gerry Anderson made a conscious effort to make most of the characters American, in order to improve his chances of selling the show internationally. But he didn't cast Americans — most of the actors were Brits, Canadians, and Australians affecting American accents. In fact, the number of actual Americans who provided voices for Anderson's shows can be counted on one hand (David Holliday, David Healy, Robert Easton, and Ed Bishop). While the non-Americans' accents are convincing, the dialogue is still marked by word usages and slang exclusive to the UK. That didn't stop Jeff Tracy from putting on a bad English accent as a joke:
Jeff Tracy:[badly pulling off a British accent] Oh, bang on. Jolly good show.
A mild example in Timeless, where the Ohio native Matt Lanter is playing the Texan Wyatt Logan. Interestingly enough, Garcia Flynn (played by Croatian-born Goran Vinjić) never attempts an American accent (justified, as he was born overseas), even when he pretends to be a US government agent.
Titans (2018): Americans Dick Grayson and Rachel Roth are portrayed by Australian actors Brenton Thwaites and Teagan Croft. Also, American Bruce Wayne portrayed by Scottish Iain Glen.
Torchwood: The fourth series (Torchwood: Miracle Day) mostly takes place in the US. There is a scene where Eve Myles (Welsh) and John Barrowman (Scottish) pose as an American couple to get information. For two sentences, Eve does a pretty convincing American accent, but coming from her it sounds creepy, as she normally has a pretty thick Welsh accent.
Trinkets: Kiana Maderia, who plays American teen Moe, is a Canadian.
Alexander Skarsgård (mentioned above) sports an American accent to play Eric Northman, a vampire from Scandinavian Europe (like his actor) who has lived in America for many years.
British actor Stephen Moyer and Canadian-New Zealand actress Anna Paquin also both sport southern American accents to play Bill Compton and Sookie Stackhouse, respectively. Moyer has had a few instances where his real accent slipped through.
Australian actor Ryan Kwanten plays Sookie's brother Jason Stackhouse.
In-universe with Russell Edgington. He is played by the Chicago-born Denis O'Hare, who puts on a Southern twang as Russell. According to the actor, Russell was a Druid priest before he was a vampire, and this accent shows itself whenever Russell gets angry.
Elena is played by the Bulgarian-born Canadian Nina Dobrev.
Several of the Originals (at least Klaus, Rebekah, and Kol plus the dead son Henrick) were born in the New World, making them American, and they are not played by American actors.
Veronica Mars features mostly American characters, some of whom are played by non-Americans. Notable examples include Keith Mars (Canadian Enrico Colantoni), Duncan Kane (Australian Teddy Dunn), Meg Manning (Israeli Alona Tal), and Parker Lee (Argentine Julie Gonzalo).
Jaime Murray (British) temporarily has an American accent after her character Helena Wells undergoes Laser-Guided Amnesia and is programmed to think she's an American schoolteacher.
The Wilds: Australian actors Mia Healey, Rachel Griffiths, Shannon Barry and Michael Teh are playing Americans. New Zealand actresses Erana James and Sarah Pidgeon too. Jenna Clause is Canadian playing American.
Sheffield, England-born Dominic West as Jimmy McNulty. Not only does he do a convincing accent, he does a decent job at a very local Baltimore accent (when he's pretending to be the non-existent serial killer on the phone). At one point in season 2, McNulty infiltrates a brothel while posing as a British businessman, and his "fake" British accent is hilarious — and "improves" so quickly that by the end of it, he's speaking in West's natural accent.
Londoner Idris Elba as Stringer Bell. He was so dedicated to his accent and so good at it that he used his Stringer Bell voice during promotional appearances in order to avoid disturbing Wire fans.
The Irish-native Aiden Gillen plays Italian-American Tommy Carcetti. You can only tell if you listen really closely.
Without a Trace: Anthony LaPaglia (Jack Malone), Poppy Montgomery (Sam Spade), and Marianne Jean-Baptiste (Vivian Johnson). The first two are Aussies, the latter British. The Australians are stuck with the common problem that they've spent so long in the U.S. doing American accents that Australians think their natural Aussie accents are fake.
Kiwi Lucy Lawless uses a flawless American accent, and it's startling to hear her native, higher-pitched accent in interviews.
Some of other regulars, such as Karl Urban (Caesar) and the late Kevin Smith (Ares), also pull off fake Americans. But there are plenty of other minor villains who... don't.
The characters in Hercules: The Legendary Journeys and Xena all use American accents; a particularly jarring example is Claudia Black as a minor character in both. For people used to her normal accent (which is already a strange conglomeration of Australian and English anyway), her attempts at speaking with an American accent are even more distressing.