First off, read Werewolf of Paris by Guy Endore. It is considered the Dracula of the werewolf genre.
Murcheston: A Wolf’s Tale by David Holland. This is a great new novel in the genre in
the style of Dickens. Find this and
Wilderness by Dennis Danvers. (My girlfriend really liked this one). A non-horror novel about a woman having to deal with love and lycanthropy.
White Wolf by Franklin Gregory
Wolfen by Whitley Strieber
The Howling by Gary Brandner
The Beast Within by Edward Levy (not really a werewolf novel)
Crooked Tree by Robert C. Wilson (were-bear, really good)
The Orphan and The Captive by Robert Stallman
Cycle of the Werewolf by Stephan King
The Totem by David Morrell
Saint Peter's Wolf by Michael Cadnum
Werewolf! edited by Bill Pronzini. A great collection of short stories.
Darker Than You Think by Jack Williamson. It's a little old but it's great.
Wolf Leader (Meneur des Loups) by Alexandre Dumas. It's a good Faustian tale of werewolfery even though he doesn't turn into a werewolf until the last two chapters.
by R.M. Reynolds. An old
Dr. Jekell and Mr. Hyde. It's not a werewolf but it does present the duality of man better than most any other book.
Book of Were-wolves- Sabine Baring-Gould
The Werewolf- Montague Summers
The Beast Within- Adam Douglass
Werwolves- Elliot O'Donnell
Werewolf Delusion- Ian Woodward
Lycanthropy Reader- Charlotte Otten
Origin of Werewolf Superstitions- Caroline Taylor Stewart
The Werewolf; in Legend, Fact and Art- Basil Copper
Man into Wolf : An Anthropological Study of Sadism, Masochism, Lycanthropy by Robert Eisler. Lecture.
The Complete Book of Werewolves by Leonard R. N. Ashley. Not “Complete” but still pretty good.
Meet the Werewolf (The Eerie Series) by Georgess McHargue. A good starter for younger readers.
Some of the non-fiction books are quite heavy, Montague's book esp. (knowledge of French, Latin, Spanish, Olde English, and German is helpful as he doesn't translate many quotes). Stewart's thesis is good but really hard to find. It's not all that important if you can't find it. Baring-Gould's book is a must have. I like O'Donnell's book too but it's a little harder to find. O'Donnell did a lot of first hand research and you will find him quoted in about every werewolf book. Woodward's and Copper's are two good new ones that include some good filmography stuff. The Beast Within is a great collection of essays on werewolf topics. There is a separate werewolf filmography book, if you really like bad werewolf movies you might want to check it out, it's written by Stephen Jones. The Lycanthropy Reader is a collection of the major articles, papers, etc on werewolves. You'll find the legend of Lycan, Peter Stubbe, essays on werewolves etc. I read Ashley's "Complete" Book of Werewolves that came out last year. The guy didn't bother to do his research and gets a lot of stuff wrong. Much of it is incomplete and he admits it in places. He does cover rpg games which the other books do not. Other than that, it's not worth the money. These works will give you a great foundation. If you need any help finding something specific or something hard-to-find, email me. If it's about werewolves, I've found it. Don't be afraid to ask for your librarian's help. Interlibrary loan is a God-send. www.searchbiblio.com will help you find good used copies for cheap. If you are looking for aspects other than what I’ve listed here, I can recommend some of those too.