No-party Candidates?
The only successful presidential candidate before Donald Trump who lacked any roots in the nominating party that I can think of on the spur of the moment is Zachary Taylor, who had never voted or served in political office before his election as a Whig in 1848. Military officers like Eisenhower and Grant had been courted by both parties, as Taylor was, but they did have some connection to the Republicans who nominated them and they ran on platforms fairly consistent with the party's past policy positions. Am I missing someone else?
Peter