The answer to that question would be Dwight D. Eisenhower, since none of his pre-president jobs were technically elected office. He was a military man for most of his life, was appointed Supreme Allied commander in Europe during World War II, and was a military governor briefly after the war. In between then and 1952, he was President at Columbia University and NATO Supreme Commander, which are also not technically elected office.

I'm going to make a large set of assumptions about what you're asking specifically, then answer that question instead.

I'm guessing you're asking about the United States, in relation to Donald Trump's current run for office. If we limit ourselves to the United States, then the major parties are the Democrats and Republicans. If we're looking at specifically candidates for the Presidency, then the answer is Dwight D Eisenhower.

Eisenhower was elected in 1952, and prior to that had not held elected office. He had, however, been a five star general in the United States Army, president of Columbia University, Supreme Commander of NATO, and the Military Governor of Germany.

If you're just looking for any Democratic or Republican Candidate in any election at a state, local, or national level, then I'm afraid I have no idea, but maybe someone else can help you.