Here is an article with 10 Free eBooks for Halloween. For the people that like to fetch the eBooks from Amazon, here are the links. Not all of them are free from Amazon and for some titles I didn't find a cheap version that I could recomend.

Frankenstein

Dracula

STRANGE CASE OF DR JEKYLL AND MR HYDE - ORIGINAL VERSION PUBLISHED FOR KINDLE - UNIQUELY ILLUSTRATED VERSION - R.L. STEVENSON ILLUSTRATED

The Shunned House

Fall Of The House of Usher - The Complete Works of Edgar Allan Poe (Includes Essay About the History of the Horror Genre)

Tales of Terror and Mystery Illustrated

Extra: Dracula's Guest