(Farmer himself died a few years ago, at only 62, of a sudden heart attack in his sleep, but he seems to have put in about 100 lifetimes worth of work. One wonders if his legendary overwork contributed to an early death.)
Farmer grew up incredibly poor, got into Duke and Harvard, had opportunities to make incredible money and traded it for a life of providing medical care to the third world on a shoestring budget while schooling organizations like the WHO on how to provide care along the way.
Truly one of one.
On top of that he was incredibly competent at navigating the combination of hostile bureaucracy, apathy, and disorganization. It's incredible what he and PIH accomplished.