We Americans use John Smith as the most common or default American name. What name is instantly evocative of a culture/ethnicity/nationality? I’ll start:
Irish - Patrick O’Brien
I just read something that “Garcia” is going to be the most common surname in the US because of the increasing Latino population, so I guess “Garcia” would be the “SpanisH” version. No idea what the first name might be…Juan?
Or Jose. I personally know 3 Jose Garcias.
This probably varies regionally, but at least here in Panama González is much more common than Garcia: 34 columns vs 13 columns in the phone book.
Regarding the OP, what is the basis for selecting that particular Irish name rather than many others?
Vietnamese is easy, at least as far as last name. Nguyen is by far the most common last name in Vietnam, and has flummoxed American attempts to pronounce it for decades. For first name I would go with Dai, Dat or Phuoung.
Don’t know about first names, but it seems as if every other Indian I meet at work has the last name Patel. Anyone out there who can say if this is a common surname in India?
Danish: Lars Larsen. Or Hans Hansen, or Jens Jensen. Take your pick. 
Russian: Ivan Ivanovitch, but someone will have to supply a proper last name.
Any Arabic country - Mohammad. No particularly common surnames, though.
Oh, this isn’t going to be an exact science. It’s just a name that would prompt my Irish-American father to exclaim, “he’s as Irish as Paddy’s pig.” I have no idea what that means, but I know that if somebody is named Patrick O’Brien, chances are good that that person is Irish.
So pick a culture you have had some exposure to and pick a really common name. Have fun - there aren’t any right answers.
(Hey, you guys are cheating. I want first and last names!)
My vote for Mexico is Jose Luis Rodriguez.
Here is a listing of common last names:
http://en.wikipedia.org/wiki/List_of_most_popular_family_names
For China it would be Wen Chan.
For Japan, Hiroshi Sato.
For Russia, [first name?] Ivanov.
I like the 9th most common Japanese name.
Yeah, it’s really common. I’ve heard that it’s most common in the northwest part of the country, and that a lot of people emigrate here from there, and that’s why it seems so common in the States, but I have no cite. Hopefully, someone could tell us whether that’s true. I do know that in central Jersey, you can barely turn around without running into a Patel. You know how at the pharmacy, they have bins for the finished prescriptions–a bin for each letter. Well, I’ve seen pharmacies around here where there is a bin just for the Patels!
So, for Indians, I’d nominate Raj Patel. In the company I used to work for, there was a department with only 4 people. 3 of them were named Raj Patel.
It’s interesting, USA and UK have very similar top surnames, but Quebec and France are quite different.
Ivan Ivanovitch Ivanov – their equivalent of “John Doe.”
Germany: Hans Mueller
France: Jean Deau (HAHA! Get it?)
California: Sunshine Moonflower
giggling softly to aviod detection by coworkers
Kim seems to be a very common Korean surname and for some reason Kevin seems to be popular when picking an anglicised name.
I have met more Kevin Kims then John Smiths (though I am a Smith, by marriage and I hate the bloody name)
I’d have to nominate “Paddy Murphy” as the archetypal male Irish name. (I say this as someone whose mother’s name is Rosie O’Rourke, and whose grandmother’s name was Mary MacNamara.)
Not exactly the subject, but in Spanish the equivalent of “Tom, Dick, and Harry” is “Fulano, Mengano, and Zutano” (and other variants, but the first one is always Fulano). “Joe Blow” is “Fulano de Tal.”
Here’s a listing of international “anonymous names” (John Doe/Joe Blow/Joe Bloggs). Not exactly what the OP is asking, but it probably has some archetypal names too. Another one they give for Spanish is “Juan Perez.”
[Jon Arbuckle]“I wouldn’t say you’re fat, Garfield, but you have more chins than the Hong Kong phone directory.”[/Jon Arbuckle]