Defining a Thriller

As a genre Thrillers are hard to define to one exact type of film, within the thriller genre there can be sub cataories. These can include such things as horror type thriller, Crime thriller, spy thrillers , there are many variations. Thrillers are films that can have a "who done it" fel to them and can generally create alot of questions for the viewer, example of a thriller may be : Source code, The James Bond films, The bourne films , Hostage , Vantage point, Taken.
These are examples of different types of thriller's film posters: