Where might one find the undead, if one is compelled to look, if out of macabre curiosity? There are certain locales in an imaginary world where they can be found though it is not 100% guaranteed. Where they appear depends on the world and where their creator placed them.
One area that they call home across many imaginary worlds is the tombs. As the resting places of people who lived and died throughout the ages, they are the perfect place for the undead to roam. They come to life through a myriad of means and most of the time, they do so in order to protect the catacombs from looters and other intruders.
The fantasy undead also has a strong association with cemeteries — no surprise there — making these sites excellent places to harbor them. However, they do not appear during the daytime, choosing only to come out of the ground when the sun has set and night has descended upon the landscape. They groan and wail as they walk around the graves until the first light of the new day begins to creep in and then they instantly disappear underground.
As beings who despise the light, the walking corpses prefer areas far removed from them. Caves, temples, and dungeons are just several locales where they reside. Their purpose is the same as that of the tombs: to guard against outsiders, notably those who seek treasure.
When darkness reigns supreme, the fantasy undead are more emboldened than ever, appearing in far more places than they did previously due to ceaseless gray skies that blot out the light. They can move in cities and drive out the living, show up in fields and terrorize all travelers, and even take control of forests and drain all their vim and vigor.
Many stories and worlds feature the undead in some capacity. As a servant of darkness, their mission is to hinder the protagonist’s efforts in saving the world by instilling fear in the populace and making it difficult for them to muster up enough courage to face them head-on. When push comes to shove, they will enter the battle against the hero and deploy all their powers in an effort to prevent him from succeeding against the forces of evil.