For Christmas Eve: an old Greek folk tale:
There is a very old tree, the Tree of Life, that holds all of the earth on its branches and leaves. This tree is very deep down inside the earth, and all around the year, there are some small and evil creatures (kallikantzaroi) that try to cut the tree off, some with saws, some with axes, some with hatchets. They look like small demons (I think the closest thing would be goblins), some tall, some short, but all of them ugly. At December 23rd, when the waters are unbaptized (Christ is born, but is not yet baptized), they come up to the surface to tease people and generally have fun. They come into the houses and spoil what is not in order, they come and scare people that are walking by themselves in the night, and they are a general nuisance. They may not kill humans, but they can steal their voice, if they don’t answer some questions. At Epiphany (January 6), a priest comes and blesses each house with Holy Water. The kallikantzaroi are burned (kind of like vampires) by the Holy Water, and they rush back into the Earth. Meanwhile the Tree of Life has regenerated, so the kallikantzaroi have to spend the entire year cutting and sawing the Tree of Life again!