The Chain of Harm

A very messed-up theory as a variant of typical karma. The basic premise of karma is something like this: "Don't do something bad, because later something bad will happen to you." This, on the other hand is quite different.

As a scenario, a man running a company is under a great deal of pressure from his superiors to produce the product faster. He's just been yelled at. Obviously, he can't talk back to his supervisor since he'd get fired, so what does he do? He yells at his normally best worker on something small. Well, the target man doesn't want to be known as the guy who beats his wife, so he shouts at her when something wrong happens. Because of the marital strife, she screams at her kid all the time. The child has no weaker human to take it out on, so the kid beats the family dog, which bites the nearby cat. And so on. The strong harms the weak, who gives similar treatment to the weaker, who in turn harms the next weaker.

This theory has a number of assumptions:

There may or may not be an original source (in the latter case, it is because the source is oddly cyclic, or the superiors in question just an excuse used by a Jerkass boss, doing this For the Evulz).
Things often worsen when the effect changes species (the boy beating the dog, when the others simply shouted at their target).
The chain either loops back to its original source, or ends with a designated scapegoat, which is then summarily killed.
The scapegoat in question is often not human and an animal viewed as a pest. In the above example, this would probably continue on from the dog, to cat, ending with a rat being killed. It Gets Worse, if the animal has some productive use (such as rats clearing the street of insects), since their normal prey will now come along with a vengeance.
If it doesn't end with the original cycle, this harm will continue until it degrades the quality of the world, or until it reaches the original abuser, who will then receive their punishment.

Contrast to Cycle of Revenge, which directly targets the person causing harm. Compare to Revenge by Proxy, Delegation Relay.

Examples of The Chain of Harm include:

General

This is often played out in various stories of revenge or horror. But it can also be Played for Drama (a family is at the end of the chain, or an oppressor is at the beginning and gets his comeuppance), or Played for Laughs (slapstick, such as a situation where one person hits a guy with a hammer, and he can't hit back, so he kicks a cat or something).
Some of the more "realistic" revenge plots might use this to demonstrate a trickle-down effect of bad deeds as part of An Aesop rather than a direct effect of someone retaliating.

Literature

In Stranger in a Strange Land, this trope, exhibited by monkeys in a zoo, causes Michael Smith to laugh for the first time and allows him to start to understand humanity.
Good Omens has Crowley rely on this, having shut down mobile phone service in London for several minutes during busy hour, which he expects to produce a lot of angry executives who take it out on subordinates and so on. He views it as a much more efficient method of spreading pain and misery than the usual demon noble's gradual corruption of righteous or powerful individuals, something that none of them are able to understand or appreciate.

Live-Action TV

In How I Met Your Mother this is known as the Chain of Screaming. When someone screams at a subordinate, the subordinate must scream at someone lower, who in turn screams at someone else, and so on until someone screams at the original screamer and the cycle is complete. Marshall's attempts to break the chain do not go as well as he hoped.
Discussed (and simultaneously played out) in Blackadder III:

Blackadder: It is the way of the world, Baldrick: the abused always kick downwards. I am annoyed, and so I kick the cat; the cat pounces on the mouse; and, finally, the mouse bites you on the behind.
Baldrick: And what do I do?
Blackadder: Nothing. You are last in God's great chain.

Newspaper Comics

Seen in this Dilbert strip.
For Better or For Worse illustrates this in several strips. One Sunday comic shows the trickle down effect with a frustrated and exhausted Elly yelling at Michael over some slight, followed by him going after their dog Farley. Farley barks at Elizabeth, who throws her stuffed Bun-Bun down as the punchline.

Video Games

Oracle of Tao is the trope namer of this. Oddly enough, despite being given an explanation of this, it is not actually carried out in the game.
- Although it is referenced again in the Playable Epilogue, and the Hero Antagonist has to pick up the pieces.

Western Animation

Played for Laughs in Avatar: The Last Airbender. Katara tries to get caught "earthbending" (it's complicated) so she insults Sokka calling his ears big in a fake argument, and Aang uses a sewer grate to airbend a rock. Afterwards, Sokka says, "Momo, you have some big ears."

Real Life

This actually seems to happen in Real Life with cycles of abuse, though probably not to quite this extent.
The inverse of this (in terms of order) sometimes happens in spraying pesticide. Rats eat plenty of bugs, which then snakes eat plenty of, which birds like hawks eat. The hawks usually end up sterile.