Other forms: typecasting; typecasts
To typecast someone is to repeatedly identify or represent them as a stereotype. Directors and casting agents routinely typecast actors, choosing them for extremely similar roles over and over again.
Think of an actor who always plays a superhero and is never chosen to play a romantic lead or the main character in a historical drama. That actor is being typecast. Sometimes performers intentionally seek out unusual or challenging roles in order to avoid this kind of stereotyping: if the child star of several peppy sitcoms suddenly plays the villain in a gory horror movie, you can bet that she doesn't want to be typecast.