The Lares and Penates of Ancient Rome are perhaps the best-known example of household gods, but many others existed. The hippo-headed Tawaret was a popular element of ancient Egyptian mythology; she was considered to be the protector of women during pregnancy and childbirth. Bes was another popular Egyptian household god, whose duties included killing snakes, protecting children, encouraging fertility, and assisting Tawaret in childbirth.
Household deities were usually worshipped not in temples but in the home, where they would be represented by small idols (the teraphim of the Bible), amulets, paintings or reliefs. They could also be found on domestic objects, such as cosmetic articles in the case of Tawaret. The more prosperous houses might have a small shrine to the household god(s); the lararium served this purpose in the case of the Romans. The gods would be treated as members of the family and invited to join in meals, or be given offerings of food and drink.
Although the cosmic status of household deities was not so lofty as that of the Twelve Olympians or the Aesir, they were also jealous of their dignity and had to also to be appeased with shrines and offerings, however humble. Because of their immediacy they had arguably more influence on the day-to-day affairs of men than the remote gods did. Vestiges of their worship persisted long after Christianity and other major religions extirpated nearly every trace of the major pagan pantheons, and indeed, they continue even today, in one form or another.
For centuries Christianity fought a mop-up war against these lingering minor pagan deities, but they proved tenacious. For example, Martin Luther's Tischreden have numerous quite serious references to dealing with kobolds. Eventually rationalism and the industrial revolution threatened to erase most of these minor deities, until the advent of romantic nationalism rehabilitated them and embellished them into objects of literary curiosity in the 19th century. Since the 20th century this literature has been mined for characters for role-playing games, video games, and other fantasy personae, not infrequently invested with invented traits and hierarchies somewhat different from their mythological and folkloric roots.
The real religion of Japan, the religion still professed in one form or other, by the entire nation, is that cult which has been the foundation of all civilized religion, and of all civilized society,--Ancestor-worship.
Drawing the picture with broader strokes. he continues:
Three stages of ancestor-worship are to be distinguished in the general course of religious and social evolution; and each of these finds illustration in the history of Japanese society. The first stage is that which exists before the establishment of a settled civilization, when there is yet no national ruler, and when the unit of society is the great patriarchal family, with its elders or war-chiefs for lords. Under these conditions, the spirits of the family-ancestors only are worshipped;--each family propitiating its own dead, and recognizing no other form of worship. As the patriarchal families, later on, become grouped into tribal clans, there grows up the custom of tribal sacrifice to the spirits of the clan-rulers;--this cult being superadded to the family-cult, and marking the. second stage of ancestor-worship. Finally, with the union of all the clans or tribes under one supreme head, there is developed the custom of propitiating the spirits of national, rulers. This third form of the cult becomes the obligatory religion of the country; but it does not replace either of the preceding cults: the three continue to exist together.
As stated in the Wikipedia article on Shinto,
Whenever a child is born in Japan, a local Shinto shrine adds the child's name to a list kept at the shrine and declares him or her a "family child" (氏子 ujiko). After death an ujiko becomes a "family spirit", or "family kami" (氏神 ujigami).
Many Japanese houses still have a shrine (kamidana "kami shelf") where offerings are made to ancestral kami, as well as to other kami.
Larva betrays its affinity to lar..., and the good kindly lares were often held to be manes or souls of departed ancestors. So in our German superstition we find instances of souls becoming homesprites or kobolds, and still oftener is there a connexion between unquiet spirits and spectres.
To underscore the equivalence of brownie, kobold and goblin, consider the words of the English historian and folklorist Thomas Keightly:
The Kobold is exactly the same being as the Danish Nis, and Scottish Brownie, and English Hobgoblin. [b] He performs the very same services for the family to whom he attaches himself....
The Nis, Kobold, or Goblin, appears in Scotland under the name of Brownie.
What are our elves and fairies, goblins, nisses, brownies, and pixies but latter-day survivals of arkite ancestor worship? Brownies and pixies were probably invariably of good character, originally, a likelihood suggested by the good points which in many respects survive in their character, their virtues being turned into vices, and, contrariwise, their vices into virtues, as good or ill fortune befell the household and its appurtenances. Is not the bowl of milk placed for the Brownie in the corner of the room a survival of the drink-offering of wine which was poured out before the household gods of the Romans?
The term fairy, however, is also loosely used to include other beings of a similar character like the brownie, elf, fay, gnome, goblin, kobold, pixy, puck, salamander, sprite, sylph, troll and undine....Fairy lore containes likewise certain elements of ancestor-worship, of mythology, and of older religious beliefs....
The resemblance to the Robin Goodfellow (q.v.) of the English and the Kobold of the Germans is conspicuous, and the Roman Lar is also suggested by this suspicion.
The belief which guided the conduct of our forefathers was .... the spirit rule of dead ancestors.
In Section 2 he proceeds to elaborate:
It is thus certain that the worship of deceased ancestors is a vera causa, and not a mere hypothesis....
In the other European nations, the Slavs, the Teutons, and the Kelts, the House Spirit appears with no less distinctness.... [T]he existence of that worship does not admit of doubt.... The House Spirits had a multitude of other names which it is needless here to enumerate, but all of which are more or less expressive of their friendly relations with man.... In [England]...[h]e is the Brownie....In Scotland this same Brownie is well known. He is usually described as attached to particular families, with whom he has been known to reside for centuries, threshing the corn, cleaning the house, and performing similar household tasks. His favorite gratification was milk and honey.
The second phase of this stage of thought [Animism] would be a cult of human ancestors, specially of tribal chiefs and clan-heroes: this is Manism or Ancestor Worship proper, culminating in hero worship....it is to be noted that the characteristics pertaining to a particular clan or tribal community, which mark ancestor worship, will have fallen very much to the background if they can be at all inferred among the Celts; the relations emphasised will be found pertaining to mythologic concepts and to the Nature-Myth. For, as modifications and transitions in behalf are constant, ancestor worship gets partly transcended. But in Manism the guardian spirit has its specific influence on the tribal consciousness. I recollect Aoibhell of Craig Liath, the guardian spirit of the Dal Caiss, mentioned in the narrative concerning Brian Boru in the Wars of the Gaedhel and the Gall; there is also Mag Molach or Hairy Hand, and Bodach An Duin of Rothiemurchus, as well as the more familiar belief in the Brownie which renders offices of help in some houses,—a feeble survival of early phases of cult.