The most famous populist is probably William Jennings Bryan. He rode a wave of man of the people appeal and almost won the presidency before the age of forty on a third party ticket.
The interesting thing about populism is that it doesn't fit into any traditional ideology. Anyone can be a populist because all it really means is a politician that is in touch with the thoughts and beliefs of the people. The "folks" is what Bill O'Reilly calls them as he applies his own brand of populism on his show.
Only three or four years ago, populism was associated with such concepts as universal health care, protecting U.S. jobs, and tax increases on the wealthy. That's why it's none too ironic that fiscal conservatism is the new populism.
That's the greatest accomplishment of the Tea Parties. They were the greatest visual evidence that the folks care about government spending, out of control government, and deficits. It was cool to be fiscally conservative.
This isn't only ironic but natural. It was populist to be for universal health care when that was merely a concept. When the folks got the bill for universal health care, the folks wanted someone that could spend their tax money wisely. Now, if you want to be a populist, you have to get your fiscal conservative bonafides.
Please check out my new books, "Prosecutors Gone Wild: The Inside Story of the Trial of Chuck Panici, John Gliottoni, and Louise Marshall" and also, "The Definitive Dossier of PTSD in Whistleblowers"