Produced by Steven Spielberg and written by Chris Columbus (who would go on to direct the first two Harry Potter movies), Gremlins brought a big-Hollywood sensibility to midnight monster movies. Starring Zach Galligan and Phoebe Gates, this modest-budget film was a hit when it debuted in 1984 and went on to gross over $150 million.
Gremlins is the story of Billy (Zach Galligan), the son of a not-terribly-successful inventor. Billy is still living at home while working at the local bank, dreaming of one day being an illustrator, as well as, perhaps, his co-worker Kate (Phoebe Cates). His life changes when his Dad (Hoyt Axton) brings home a strange Christmas present for him, a mysterious but cute creature known as a Mogwai. He is named Gizmo, and is pretty low maintenance as long as you remember three very important rules: he's afraid of bright light, so never leave him in direct sunlight; never get him wet; and don't feed him after midnight.
Well, guess how long it takes one of those rules to be broken? Soon, Gizmo has spawned further, more-violent versions of himself that are not only causing havoc around the town, but are able to multiply themselves rapidly. Before long, the whole town is at the mercy of these gremlins and Billy is trying to save Kate from them as well as restore things back to normal.
The main problem with Gremlins is that it tries to be about three films at once. It's a monster movie about gremlins invading a small town. But it's smart enough to realize that's a bit hokey on its own, a double-feature at best. So it dresses it up as a comedy. But then there's also this small-town "But it's Christmas" setting that wants to steal a bit from A Christmas Story. It wants all of these things, but the only way it knows how to keep them all is to bounce around between them, and never truly integrate them all into a cohesive whole.
Although it does a decent job. It's generally enjoyable when you look past its obvious flaws and just go with it. But the monster emphasis is a bit too much for younger kids, and the humor is a bit too low for adults, so the fact that it's strong enough at mixing those elements could more accurately be expressed by saying that it's strong enough at straddling those ages. It's a proto-tween movie, the age where your sensibilities are still goofy enough to have fun with the corny story, but you're old enough to not be weirded out by the violence. After all, it's just a puppet in the microwave, and they never billed it as anything else.