#themarbleindex

Nico Evening of Light (1968)

I think it depends on the plot and characters of the movie.  You can take a movie like The Silence Of The Lambs that has serial killers and mild gore scenes and one could think of it as a horror movie.  It has horror elements and a lot of people probably think of it as a horror movie.  But you could qualify it as both genres.  

But a movie like Double Jeopardy is very much a crime movie as well as a thriller.  I do not remember it having very many horror elements which is why it is probably mostly listed as a thriller.   But something along the lines of Along Came A Spider might fit into both genres, depending on your perspective.