Foreshadowing
Foreshadowing is when events occurring early in the story hint to a bigger event happening later in the story. Often, foreshadowing goes unrealized until the big reveal, when the pieces start to fall together and the foreshadowing begins to make sense.
The Wife's Story by Ursula LeGuin
The Wife's Story is about a woman discovering her husband's secret. By the end of the story, it is revealed that the woman was a wolf and the husband was some sort of reverse werewolf.
This story has many examples of foreshadowing. For example, the wife describes the husband going on a hunting trip and catching nothing, "not so much as a field mouse." A human would never try to catch a field mouse, but a wolf would. The wife also describes her husband leading the singing at the lodge nights. The singing was loud, she could hear "the singing coming up through the trees." This singing was likely the howling of the wolves.
Once the wife begins to describe her husband's transformation from wolf to man, the reader starts to understand. Everything really clicks together when the wife's sister rips out the husbands throat with her teeth.
The Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson
The story of The Strange Case of Dr. Jekyll and Mr. Hyde tells the story of Mr. Utterson, a lawyer who has a strange client named Dr. Jekyll. Dr. Jekyll starts behaving strangely with a mysterious person named Mr. Hyde. For a while, Mr. Utterson tries to figure out what's going on with both of them and by the end of it, he finds that there was much more than just strange going on in their lives.
There are some examples of foreshadowing in this story. In the beginning of the story, Dr. Jekyll is said to have written a will that would transfer all his belongings to Mr. Hyde. That would be odd considering they had no relation at this point. This will foreshadow what their relationship truly turns out to be. There is also a moment in the story where Dr. Jekyll's will states that in the case of his disappearance, Mr. Hyde should take his place. This hints towards a big reveal.
Dagon by H.P. Lovecraft
'Dagon' is a story about a man recounting the terrible event that has haunted him and led to him planning to kill himself. The story involves the narrator getting stranded on a strange island that had risen from under the ocean. He found a mysterious monolith that told of giant sea-people. One of the giant sea-people appeared and frightened the narrator.
The reader knows something terrible will happen because it is foreshadowed in the man's intent to kill himself. The narrator tells the reader that he has been haunted by some event.
The appearance of the giant sea-person is foreshadowed by the monolith.
The Hanging Stranger by Philip K. Dick
The Hanging Stranger starts with a man, Ed Loyce, who was heading to work when he finds a dead body on a lamppost. He realizes that something is wrong with the town when nobody found it odd that a dead body was hung and escapes to find help, only to die by the hands of the alien invaders. At the end of the story, Clarence Mason find a dead body hanging on a telephone pole.
The Hanging Stranger uses foreshadowing in their story very briefly. For example, they foreshadow Ed Loyce's ending with him noticing the dead body at the park. This can be used as foreshadowing on what will occur to him at the end of the story. It can also be thought of as foreshadowing when he noticed the dead body and realized nobody was doing anything about it, it signaled that something was odd about everyone in the town.
I Have No Mouth, and I Must Scream by Harlan Ellison
This story tells of five people trapped in a computer generated world. The computer had been created during World War Three and gained sentience. It then destroyed all of humanity except for five and tormented those five for 109 years. In the end, Ted, the narrator, kills his four companions to save them from the hell the computer put them through, leaving himself to suffer alone.
Ted murdering his companions is foreshadowed when Ted discusses how they had attempted suicide and it had not worked. The reader may think, that if killing themselves could not work, perhaps killing each other could.