What is the historical precedent of populist presidential candidates in the United States?

Populist parties seem an inevitable part of democracy. The existence of demagogues who pander to the fear, anger, and resentment of those who feel marginalized by their societies is attested in ancient Greece; Cleon's rhetoric was in many ways similar to that of many contemporary populists.
In recent memory, Ross Perot was an example of a wealthy businessman who campaigned as an independent on a populist platform. Like Donald Trump, he stirred up nativist sentiment of the sort that is closely allied with racism, particularly directed against Mexicans. 
George Wallace was a Governor of Alabama who was strongly in favor of racial segregation. He ran unsuccessfully for President several times, on a populist platform with a strongly racist bias.
Patrick Joseph "Pat" Buchanan also was a populist to the far right, who ran in the Presidential primaries on a platform that was strongly anti-immigration, anti-Semitic, isolationist, and anti-gay, also preying on people's fears of social change. 
Earlier populist movements, especially those of the nineteenth century, were more closely allied to what in Canada and Europe were Labour parties (Labour in Britain, the NDP in Canada, e.g.), mainly concerned about the welfare of the working poor, exploitation of labor (including child labor), and income inequality.   William Jennings Bryan was an important populist candidate. This earlier form of populism was progressivist, and did much to bring in important reforms such as minimum wage, the eight-hour workday, limits on child labor, etc.