Norman Bourlaug. John Bardeen too.
EDIT:
Oh, you said vilified, not unknown. Hm...
I think LBJ, Nixon, and Bush I are rather underappreciated as Presidents, albeit the last one wasn't vilified on the level that the first and especially the second were. Truman was, but might not be this anymore.
Nixon in particular is vilified to what I do consider unfair levels. He's not the best or even a remotely top level President, far from it, but I don't consider him to be on the same level of absolute fail as Pierce, Buchanan, Carter, or Bush II. In terms of actual policy and policy proposals, foreign especially but even domestic, this was not a failed administration.
But it's popular discourse that pisses me off, the sheer lack of intellectual rigor in studying him. Just look at the story of "the plan to murder Jack Anderson." What other President would people believe the word of G. Gordon Liddy on, with nobody questioning the story? If it makes him look bad, they'll do it. MSNBC *still* won't admit that he didn't order the Watergate break in. It's just gratuitous, especially considering the last 15 years of what has happened with our government. The papers remained silent through all those abuses, tepid in their criticism at best, and still pat themselves on the back on Watergate and let us know that "Nixon was worse than we thought. Be thankful we got him." It's sickening. That was 40 years ago. Get over yourselves, we have far bigger issues.