No Country for Old Men
Author: Cormac McCarthy
Genre: Crime thriller
When the Coen brothers turned Cormac McCarthy's No Country for Old Men into the 2007 Academy Award-winning hit movie, they displayed tremendous filmmaking prowess, sure, but even Joel and Ethan themselves would admit that, really, they mainly just stayed true to McCarthy's novel. The greatness was already present in the esteemed author's dark meditation on violence, lawlessness, and helplessly watching the world change for the worst.
Fun Fact: It makes sense that No Country for Old Men eventually made a splash in multiplexes; originally, McCarthy wrote it as a screenplay, but he was never able to sell it as such.