Wikipedia
A haltija (haltia) is a spirit, gnome, or elf-like creature in Finnish mythology that guards, helps, or protects something or somebody. The word is possibly derived from the Gothic *haltijar, which referred to the original settler of a homestead — although this is not the only possible etymology.
The word is also used in modern Finnish to mean, depending on the context, holder, occupant, lord, master, owner-occupier, occupier, possessor, bearer, or owner.
There are many different kinds of haltijas. There are, for example water haltijas and forest haltijas. Even graveyards have their own haltijas (kalman väki, "death folk").
Human settlements also have haltijas. One type is the tonttu or maan haltija (land haltija). The tonttu is the Finnish version of the Swedish tomte. The Finnish tonttu and the Swedish tomte are related to the words tontti (Finnish) and tomt (Swedish), which both mean building lot and building site. (Later, such local spirits are also referred to as a tomtegubbe ["old man of the homestead"] in Swedish). The kotihaltija (home elf, home gnome) is the tonttu who lives in every home. He takes care of the house, and it is important to treat him with respect. The saunatonttu lives in the sauna and protects it but also makes sure that people do not behave improperly in it. Joulutonttu is Finnish for Christmas elf. Unlike the Christmas elves in some countries, the Finnish joulutonttu doesn't have pointy ears.
There are even personal haltijas, which are protective spirits similar to angels in Christianity. One of them is called "luonto", which means "nature".
In Estonian mythology a similar being is called haldjas, whereas the term used in Estonian for a holder, master, or owner-occupier is haldaja.
Haltija is sometimes written as haltia. Nowadays this more old-fashioned spelling often refers to the elves in Tolkien's books or other fantasy literature.