I’m really surprised no one has mentioned Lin, or Scott, or Robin Williams.
A guy like me who was not trained in a University setting, but has read hundreds of books and started drawing at 4-5yrs old and never stopped, I don’t know if there is any one resource or person.
For me it’s the journey to borrow from those that are out there. I like looking at the work of old illustrators and the work of all those draughtsman that toiled for guys like FLW, and other architects from the 1900′-1940’s great stuff.
I’d say stay with the search, it’s more fun!