I seem to recall (though perhaps age dims the memory) that I was reading (with a little help, perhaps) Howard Pyle's "Robin Hood" at the age of four or five. I suppose that wouldn't even be approved for teenagers these days, given that it involves violence, swearing of oaths*, and critical views of religious and secular hierarchy, but still.

* I suppose that's also why I startle my co-workers by saying things like "By the Rood!" and "Haste thee, crude varlet!" :-)