Not a boast of any kind, but I did spend an awful lot of my early teens reading really quite highbrow fiction, which I now really regret. Most of them I've not looked at since and it bugs me that I didn't have a 'word with myself' or, indeed have access to more appropriate material (YA didn't exist).
Mine include most of Saul Bellow (about age 13), some Somerset Maugham (ditto), Wuthering Heights (age 11, but did retread this at Uni), some of the more obscure Hardy and Zola novels (maybe age 14?)
Anyone else wasted decent lit on being too young?