Fountain Society by Wes Craven
Riding the Rap by Elmore Leonard
The Spy Who Came In From The Cold by John Le Carre
Our Man In Havana - Graham Greene
In The Dark by Mark Billingham
Generally books by Stephen King, Clive Barker and perhaps to a lesser extent Anne Rice fit quite well into the horror or fantasy genres.
For crime thrillers then Ian Rankin, Michael Connelly, John Grisham, Karin Slaughter and James Lee Burke are all decent enough to blast through but they're unlikely to challenge you if that's of interest. Christopher Brookmyre is probably one of my favourite authors although nothing of his is hugely challenging it's always lots of fun particularly if you appreciate the Scottishness of the novels. Frederick Forsythe has written some good thrillers such as the Day of the Jackal as well.
I'm missing a lot of books here as they're mostly back at my parents so it's not as long a list as I would have hoped. I would however recommend Neil Gaiman - American Gods as a fantasy novel of sorts and it's very good.