If I had my little American heart set on being the Prime Minister of, say, France, could I move over there and use my fictional millions to do it? This question is inspired by the insipid birther movement, incidentally.
Suggestion to the OP: Is your question about citizenship, or about being native-born? The USA requirement for president is more than mere citizenship, but that the person was also native-born. (IIRC, there are slightly varying interpretations of what “native-born” means, but I think the consensus is that one must be an American citizen from birth, and not a naturalized citizen.) If you clarify this now, it could prevent some confusion in later posts.
Do you want the highest rank, or the most powerful? Prime Minister/ Chancellor, or President?
In the case of Australia, the citizenship requirement is put in a negative form in section 44 of the Constitution:
Section 64 says:
This means that the Prime Minister of Australia, since she or he must be a minister of state, cannot be a citizen or subject of another country, including the United Kingdom. There is no problem, however, about the PM being born a citizen or subject of another country. Even ignoring the odd case of Chris Watson (who was born in Chile, though this wasn’t generally known until after his death), the current PM was born in Wales, and so would have been born a citizen of the U.K. At some stage she must have been naturalised as an Australian citizen, and subsequently renounced her U.K. citizenship.
In Germany, you need what’s called passive suffrage - the eligibilty to be elected for any office in an election.
** assuming you have gotten your German citizenship already as first step.
That cite is inaccurate in so far as it refers to what you call “communal”, i.e. local, level. Non-German EU citizens have the suffrage - both actively and passively - at local elections, as well as European Parliament elections. German nationality is required for state and federal elections, however.
As to the OP: A citizenship requirement in the sense that officials need to have the nationality of the respective state is pretty much standard. It’s different for the native-born requirement, which is more of a US peculiarity, even though some countries that modelled their constitutions on that of the US adopted it. Most countries will admit naturalised foreigners to their highest offices.
I snipped that part about EU-citizens being eligible at the local level because I understood the OP to be about “moving to country X [and becoming a citzen there] in order to become Prime Minister/ President”. Moving to France, get citizenship and then moving to Germany to be elected there would be more complicated.
And despite this, the British haven’t taken over any of our countries, imagine that! Democracy doesn’t collapse!
In Canada There is no requirement that the Prime Minister be a citizen of Canada.
However, there is a strong constitutional convention that the Prime Minister be a member of the House of Commons, either at the time of becoming Prime Minister or shortly thereafter, so the practical reality is that the PM must be a Canadian citizen.
Similar requirements exist to be Premier of Province.
However, there is no requirement that an MP be a natural-born citizen, nor a prohibition on dual citizenship. For example Prime Minister Turner was born in England so he might have been dual citizen, depending on the Citizenship Act that created Canadian citizenship after WW II. If so, it was never an issue.
More recently, the former Leader of the Opposition, Stephane Dion, had dual French and Canadian citizenship, but surrendered his French citizenship after it became an issue.
Of course, there is no requirement that either Her Majesty nor the Governor General hold Canadian citiznship. Our previous GovGen held dual citizenship (Canadian and Haitian) but surrendered her Haitian citiznship.
Indeed. The closest to foreigners taking over Germany which we have so far is David McAllister, currently the premier of the state of Lower Saxony. McAllister had a Scottish father and holds British citizenship. He also has, however, German nationality and grew up in Germany. The only foreign-born politician I can think of right now who had to be naturalised to be admitted to a high office in Germany was this unsuccessful Austrian-born painter in 1930.
I shouldn’t imagine Germany would fancy an Austrian as Chancellor again! Seriously though, did Hitler change his nationality when he left Austria?
Well, he solved that problem by making Austria part of Germany in 1938.
Northern Piper mentioned the Governor-General of Canada. Similar to that, there is no citizenship requirement for the Governor-General of Australia, though now there is a strong convention to that GG will be an Australian. The most recent GG to be born outside Australia was Sir Ninian Stephen (1982-1989), though he lived most of his life in Australia. The last non-Australian to be GG was William Sidney, Viscount De L’Isle (1961-1965).
Not until 1932, when he chose to run for President of Germany. Before that, even though he led the Nazi Party, he didn’t stand as part of its Reichstag slate, so citizenship wasn’t an issue. I don’t know whether Hitler would have been eligible to serve as Chancellor before 1932; since the Nazis didn’t command enough support in the Reichstag before that time, it never became an issue.
For what it’s worth, the most prominent statesman in 20th century Ireland was Eamon de Valera, who was born in New York City.
So, you certainly don’t have to be a native-born cititzen to be Prime Minister of Ireland.
For greater certainty, any elector (Canadian citizen aged over 18 on election day) may run for member of Parliament.
No, only much later. In fact, the story of Hitler’s naturalisation was quite a mess. He left Austria for Germany as early as 1913, but did not become a German citizen. Even after his rise within the NSDAP and his prominence first with his failed coup d’état in 1923 and then as a right-wing activist in Germany, he was not a German citizen - in fact, he was stateless after renouncing his Austrian nationality in 1925. Hitler did not acquire German nationality until 1932, less than a year before he seized power, and it required some effort - the branch of the NSDAP in one of the German states where it was part of a coalition government had to push for Hitler’s appointment as a civil servant, taking advantage of a law according to which such an appointment would naturalise the servant.
In the UK an MP can be citizen of one of the Commonwealth countries, or of the Republic of Ireland, in addition to the obvious. I’m unaware of any further restrictions on becoming Prime Minister - I suspect there are none.
Aaargh previous post is a bit ambiguous. To be clearer: A Commonwealth citizen, or an Irish one, is eligible to stand for election. They do not need to be a UK citizen.
Franckly, you’re asking a question I never wondered about.
The only requirment for elected postitions in France are citizenship (no need to be born here) and for the president, representatives and senators, age (respectively 23,23 and 30). European citizenship is sufficient to be elected as municipal councilior.
However, prime minister isn’t an elected position, and contrarily to, say, the UK, the prime minister doesn’t need to be a MP. In fact, one can’t be at the same time a minister and a MP.
There’s nothing in the constitution stating that members of the government (including the prime minister) need to be French citizens.
However, there could be an organic law (a statute related to the organization of public powers) stating so.
Franckly, I’m at a loss about this question. 
In Peru, for president, member of congress, minister or Supreme Court Judge you need to be natural born Peruvian.
For Regional President and Mayor you need to hold peruvian citizenship.
Oops - thanks for catching that, Matt. I mentioned it in my first draft of my reply, but appear to have edited it out. The constitutional provision is s. 3 of the Canadian Charter of Rights and Freedoms.
Note as well that it’s not a constitutional requirement that one must be a Canadian citizen to stand for election to the Commons or a provincial Legislature - it’s a statutory requirement at the federal level. In at least one Province (Saskatchewan), it’s still possible for some British subjects to stand for election to the provincial Legislature without being a Canadian citizen.