Though his films have many elements of horror not all of them would fall into the horror genre. His most well renowned piece Pan's Labyrinth is closer to a dark fantasy despite having many horror elements and The Devil's Backbone is more of a war film with a ghost story interwoven.
Del Toro has a few trademarks that he likes to include in his films. They are...
Del Toro uses children as leads or prominent roles in a number of his film. Innocence is a strong theme throughout Del Toro's film, this innocence is often set against war with a tragic ending.
Clockwork & Insect Imagery
Del Toro loves clockwork, things with gears galore and intricate parts. He is also a big fan of insects, this can be seen throughout his work from the Cronos Device (pictured above) in Cronos to big dominated Mimic and the fairies in hiding in Pan's Labyrinth.
Amber and blue hues are overly present in all of Del Toro's film. They enhance the film's visuals and work well with the copper tone of the clockwork machinery. Where there is not amber in his films, there will be blue hues, often used for dark, wet, unsettling places.
Del Toro is a fantastic director with a great eye for color and design his dark fantasy/horror films will delight and entice any lover of cinema looking for complex stories and a good scare now and then.