Possible Characters in Thriller trailer

There are lots of different characters that could be in a thriller film these could be, mum, dad, teacher, son, daughter, police, old person etc. There could be any character in a thriller film, for example the police man doesn't have to be an actual police man in a thriller film he could be just an everyday man but his job might be a police officer but during the time of the film he could be off duty therefore the audience wouldn't actually know that he works for the police. Many thriller films for example 'The Last House on the Left' have a mum or dad with a son or daughter. This is probably a common convention as lots of thriller films are based on everyday life of a family, couples or a group of things etc.