The Monster Men by Edgar Rice Burroughs (1913) is a very enjoyable one-off novel that combines a classic horror set-up with Burroughs' eye for adventure.
Professor Maxon is a brilliant and ambitious scientist who has discovered the secret to creating life, although he hasn't quite perfected it yet. After a harrowing time disposing of a body of a failed not-actually-human human in the States, Maxon decides to take his beautiful daughter Virginia and a newly hired assistant, Dr. Van Horn, to a deserted Indonesian island where he can work on his experiments without raising any questions. To help them set up shop they bring a whole gang of natives from another island, as well as their extremely resourceful Chinese cook, Sing Lee. Maxon doesn't tell Virginia what he is up to, but lays everything out for Dr. Van Horn who, in the midst of a secret escape from some unpleasant circumstances, is happy to sign on.
The experiments continue, with Maxon creating a whole stable of unsuitable Frankensteins who he uncreatively names by the order of their appearance as Number 1, Number 2, etc. until he hits the jackpot with the perfectly beefcakey specimen of Number 13. By this point Maxon has gone completely crazy and divulges his ultimate plan of breeding a perfect man to mate with his lovely daughter.
At this point, everyone wants to get with Virginia: including Van Horn, Number 13, the chief of a tribe from near-by Borneo. This lust for the beautiful woman carries us into the second half of the novel where Number 13 leads a band of his deformed brothers against the various tribes of Borneo in a quest to rescue the woman he loves (and the only woman he has ever seen), while Van Horn shows his evil side and tries to get to Virginia and her family money before the monster can make his move.
This was one of Burroughs' early books, published just a year after he delivered the one-two punch of Tarzan of the Apes and A Princess of Mars (on an unrelated note, did you know Burroughs was 35 when he published his first novel!). You can tell that he is finding his path, but regardless of your love for John Carter or Tarzan, it is just fun to read some Burroughs that isn't a part of one of his landmark series. There are some racial stereotypes to crawl over (although, surprisingly, not as many as you would think), but even with that I can't believe this one was never made into a movie.
Want to read the whole thing for free right now? Well, thanks to the power of the public domain, you can do just that right here.
[And if you are a nerd who wonders this kind of thing, I believe the edition I have, from which comes this amazing cover, is the 1963 mass-market paperback by Ace Books.]