While home invasion has been a popular motif in horror films of the 21st century, finding expression in such mainstays of the form as the aforementioned The Strangers or 2007's Funny Games - itself a remake of the 1997 Austrian film of the same name - the home invasion subgenre has been with us for as long as movies have been made. When someone forces their way in, they're not just holding us hostage - they are violating us in a very real, intimate, and personal way, just by being there.
Our homes are where we're supposed to be safe. It's the chilling motive given behind the actions of the eponymous home invaders in The Strangers, and it showcases what makes the home invasion subgenre such an effectively unsettling one.