The Drive-In Killer is the main antagonist of the 1977 cult film Drive-In Massacre. He has no identity and nothing about him is ever revealed (It is even unknown whether he is a male or female). All that is known about him is that all his known victims are all drive-in movie goers, most of whom are romantic couples and pregnant women. His only weapon of choice is a samurai sword, which he has great skill in using, demonstrated by his ability to decapitate people in one hit.
At the beginning of the film, a young couple is shown at a drive-in movie. The woman reveals she is pregnant, and the two happily celebrate in their car. Minutes later, when the man reaches out to grab the speaker, his head is chopped clean off with a samurai sword. The woman screams, but is impaled through the neck by the same sword.
The police have no leads on the murder, and don't know where to start. Soon after, another couple is murdered in the same fashion. The police investigate the theater and the manager reveals there is a man that wanders around the theater and spies on couples making out. The police decide to interrogate him. The man claims he is just a peeping tom, and that he had nothing to do with the murders. The cops believe they have their main suspect, until the peeping tom himself is murdered.
The police investigate several other leads, all believing that they may have found the killer, but all end up to be dead ends. One includes an unstable man who murdered two people and has a child as a hostage. After the madman is shot, the police believe that they have finally put an end to the killer, but then more murders happen.
While the police are still investigating a movie theater, the manager's shadow can be seen on the screen being murdered with a samurai sword.
The viewer of Drive-In Massacre is told that the Drive In-Killer is still on the run and still murdering people in theaters across the country. Then, what sounds like a public address from the viewer's theater is heard saying that a killer is loose inside the viewers theater, and the police are on their way.