Somebody, and it might have been me, but I doubt it, once said that you can tell a lot about a time period by watching their idea of horror.
So in the 30s, you've got Frankenstein. And I realize that Frankenstein was not written in the 30s, but you'll live.
Steinbeck writes of the bank: "The bank is something more than man, I tell you. It's the monster. Men made it, but they can't control it." The thing I found interesting about Frankenstein's monster is that it's not evil, especially in the movie. He's just not qualified, so to speak, to be human. He doesn't kill because he wants to destroy, he kills because he doesn't know how not to destroy. And for that matter, he doesn't even know what destruction is.
The market in the 1920s was also this giant, unwieldy monster, without a mind or conscience. The people who created the atmosphere that brought about the crash had no idea what they were doing, and didn't care that they were creating a beast; but in their defense, they had no clue what the monster was capable of.
In the 50s and 60s, Cold War. You've got space aliens and their crazy futuristic weapons. They are an evil and unseen other, and all we know is that they want to change our whole way of life or destroy us trying. What's interesting to watch is the way the terror was so close to the surface. Look at The Monsters are Due on Maple Street. If you haven't seen it, there's this street, and everybody's stuff starts turning on and off. Everybody loses power; some people get power back, some don't. Some people's cars work and others' don't. Some people have water and some don't. Everybody freaks the frick out. Finger pointing, fighting, violence, everybody terrified that their neighbor is something they're not. Turns out, spoiler alert, there are aliens turning stuff on and off as a sociological experiment. What I found weird about the episode is that I can't imagine people today reacting the same way. Actually, if the same thing happened today, a bunch of white folks would probably join together in solidarity against the nearest person of Arab descent. I'm not trying to be flip here. And that's what haunts my nightmares.
I should probably come up with more than two examples, but it's sleepy time. Perhaps there will be a part II.
Another photo courtesy of the obscenely talented Andrew Tobias Line.