Sub-genres
Political/Conspiracy
The main theme/trend in political films is the idea that someone has information that they shouldn't have. In this type of genre you'd expect to see a clear, lone female protagonist, dim lighting and an emphasis on chase scenes
Crime
Crime thrillers tend to have dark lighting, a serial killer, we do not see the killings happen like we would in a horror, more than one protagonist and they need to complement each other, serial killer will get caught and neither of the protagonists will die. Narrative is finding the killer
Psychological
The main trend/ story line in psychological thrillers is that they tend to be about ghosts, the supernatural or playing with someone's mind. Female protagonist. Pathetic fallacy. Isolated house. Ghost maybe the antagonist. Dim lighting. Features bathroom
Erotic
Erotic thriller films combine danger and romance. It plays on the idea of having an affair or an intimate relationship with someone that you shouldn't which may then lead to psychotic actions and dead. In Fatal Attractions, they use traditional erotic thriller conventions in the sense that there is an affair and it is the female that becomes psychotically attached to the male.
Medical
Most medical thrillers play on the idea of a viral infection or disease spreading and potentially wiping out large proportions of the population. Conventions shown in the trailer of I Am Legend is the idea that day is safe but night is extremely dangerous. Also plays on the convention that there is a viral infection spreading and turning people into creatures. There is a sole protagonist with a dog. The creatures being the antagonist. Sense of vulnerability while being at home.