Plan 9 from Outer Space (1959) written, produced, and directed by Edward D. Wood Jr.
Aliens plan to take over the Earth by raising an army of the dead to subjugate the living. They amass a horde of three zombies (one played by Bela Lugosi, who died a few days into the shoot) to do their bidding--terrorizing a town just outside of Hollywood, California. The residents struggle to discover what's going on in their graveyard and in the skies overhead. Meanwhile, the U. S. military gets involved, hoping to quell the invasion before the general public finds out.
This movie is legendary as one of the worst films ever made (if not the worst). In addition to the problems of low budget effects, ridiculous dialogue, mismatched studio and location shots, and the death of Bela Lugosi (replaced with another actor hiding his face with his cape), the movie also struggles with its sense of profundity. It has a big message like The Day the Earth Stood Still (in fact, practically the same anti-nukes message) but the presentation is so obvious and so overblown that viewers shake with laughter rather than fear. Many of the speeches seem crafted to sound wise and deep but come off as ludicrous. For example, the very first speech is by the psychic Criswell, who says to the camera: "Greetings, my friend. We are all interested in the future, for that is where you and I are going to spend the rest of our lives. And remember my friend, future events such as these will affect you in the future." The delivery is so earnest and so laughable all at the same time. The movie maintains a similar attempt at depth throughout. The movie tries hard to be great and fails at every attempt.
Why then is the movie still popular over fifty years later, when most other poorly conceived and executed films have been forgotten? There is a certain charm about the incompetent earnestness on display. Many science fiction cliches (flying saucers, ray guns, arrogant and superior aliens who we can beat more or less easily) are used in the most stereotypical manner possible. When an actor accidentally knocks over one of the cardboard tomb stones during a shot, that's left in rather than redone correctly or edited out somehow. The movie is much funnier (even though unintentionally) than many comedies.
I can't really recommend the movie on any artistic or moral level but it does have entertainment value. If you are curious about it, you should give it a watch. At 79 minutes, it comes and goes quickly. There are other longer, more serious, more arty films that I'll never watch again (I'm looking at you, The New World), but if someone wanted to watch this, I'd rewatch it with them. Maybe I should be ashamed of that, but that's me.