He was not, by all accounts, a man who suffered gladly, and it seems fair to conclude that he regarded almost everyone who disagreed with him as a fool. According to the Dead's Jerry Garcia, There's nothing wrong with Bear that a few billion less brain cells wouldn't cure, while lyricist John Perry Barlow is on record as saying If you wanted to be an idiot and do something any way but his, that was your decision. And he was not surprised you would choose to be an idiot. Because you were. And he was probably right.
More along the same lines here.
Perhaps the most extreme example of his idiosyncrasies was his belief that humans should be totally carnivorous and the fact that he claimed to have existed on a diet of meat, eggs, butter and cheese since 1959.
The grandson of a US Senator and Governor of Kentucky, Stanley ended up in Berkeley in 1963 after an enlistment in the US Air Force and a spell studying ballet in Los Angeles. Involvement with the production of what he subsequently labelled the sacramental substances predictably led to legal entanglements and a spell in prison, and after he was released he returned to work with the Dead, and migrated to Australia after becoming convinced that it was the most likely place to survive an imminent ice age.
Obituaries often end with the suggestion that we'll never see his like again, but in Owsley's case that statement is truer than most.
Some links:
Heads Bowed in Grateful Memory and Electric Kool-Aid Marketing Trip (The New York Times)
Owsley Stanley - '60s counterculture icon - dies (SF Gate)
The Dead Recall the Colorful Life of LSD Pioneer Owsley Stanley (Rolling Stone)