Thriller target audience

The target audience depend on the kind of thriller film. Like all other genres there are sub genres that give a specific target audience. The age group of the target audience is around 16-25 years.
The Silence of the Lambs opens by introducing to FBI trainee Clarice Starling (Jodie Foster), a student who has been selected by Jack Crawford (Scott Glenn), the head of the FBI's behavioral science unit, to help in the pursuit of a serial killer called Buffalo Bill, who skins his victims after murdering them.

 Silence of the lambs and No country for old men are both considered as thrillers and rated (R), their target audience was probably for the young male adults. 

Silence of the lambs is an 18, and no country for old men is a 15, this is because Silence of the lambs has a sub-genre to it which is horror, so there is suspected gore. Whereas with no country for old men is more of just a thriller.