These examples are taken from Eight Things You Need to Know to Write a Novel (for sale from this website)
Some will argue the following list of genres made popular by today's fiction market. To further convolute the issue, genres can be broken into sub-genres, and sub-sub-genres.
Inspirational, Coming of age, Detective, Fantasy, Educational. Example: J.K Rowling - Typical length: 2,000 - 145,000 words
Who-dun-it, Crime, Murder. Involves a puzzle that is solved by the protagonist thwarting the antagonist. This genre often includes a red-herring (someone who leads suspicion away from the true criminal). Examples: Sue Grafton, James Patterson - Typical length: 50,000 - 95,000 words.
Cozy or Amateur Sleuth: A traditional mystery with less violence. The puzzle is solved by a non-professional, i.e. an everyday person. Can include Chick/Hen Lit. Examples: Agatha Christie, Janet Evanovich - Typical Length: 60,000 - 95,000 words.
Hard-Boiled (Noir): A private detective solves the crime through action and deduction. Examples: Robert Crais, Stuart Woods - Typical Length: 80,000 - 100,000 words.
Police Procedural: Solved through law-enforcement officials, involving technical and investigative specialties and forensics. Has lots of action, blood, violence, and you can toss in a serial killer or stalker. Examples: Ed McBain, Patricia Cornwell - Typical Length: 60,000 - 95,000 (Also can include: Caper, Historical, Legal, Series)
Conflict and resolution between a couple, often has a happy ending.
Romantic Suspense, Historical, Contemporary, Series Romance, Futuristic/Paranormal, Inspirational/Christian, Romantic Comedy. (Also may include: Chick/Hen Lit, Action/Adventure, Americana, American West, Erotica, Gothic, Steampunk.)
Conflict between a villain and the protagonist, against all odds, break-neck pace, extremem action. Often the reader knows who did it. Examples: Richard A. Clarke, Dean Koontz - Typical Length: 65,000 - 75,000 words
THRILLER SUB-GENRES INCLUDE:
Conspiracy/Espionage: Situations arising from government secrecy and security, and the corrupting influence of power. Examples: Robert Ludlum, Vince Flynn - Typical Length: 90,000 - 120,000 words.
Medical Thriller: Dean Koontz
Legal Thriller: John Grisham
Techno Thriller: Tom Clancy
(Can include: Disaster, Eco-thriller, Treasure seeking, Adventure)
Urealistic in nature, from the imagination, utopian, alternate history, apocalyptic. Examples: Ayn Rand, Orson Scott Card - Typical Length: 70,000 - 200,000
Science Fiction: Robert Sawyer
Fantasy: Dennis McKiernan
Horror: Stephen King
Urban Fantasy: Stephenie Meyer or Carrie Vaughn
(Can also include: Steampunk, Alternative reality)
Set in the American West, usually in the past, but current issues are also popular. They may include elements of the above genres. Example: Cormac McCarthy, Tony Hillerman, Michael Blake - Typical Lenth: 65,000 - 90,000 words.
YA - YOUNG ADULT
Includes many of the above themes set among teens. Examples: Holly Black, Stephenie Meyer, James Patterson (Maximum Ride Series) Word count varies.
I quote E. L. Doctorow: "...writing a novel is like driving a car at night. You can see only as far as your headlights, but you can make the whole trip that way."
Whatever your genre is, enjoy the journey!