Liminal deity

A liminal deity is a god or goddess in mythology who presides over thresholds, gates, or doorways; "a crosser of boundaries". Special types include dying-and-rising deities, various agricultural deities, and those who descend into the underworld: crossing the threshold between life and death representing the most fundamental of all boundaries. Vegetation deities in particular mimic the annual dying and returning of plant life, making them seasonally cyclical liminal deities. In contrast, the one-time ordeal typical of the dying-and-rising myth, or legends of those who return from a descent to the underworld, represent a more narrow scope of liminal deities.

Etymology
The word "liminal", first attested to in English in 1884, comes from the Latin word "limen", meaning "threshold". "Liminality" is a term given currency in twentieth century anthropology by Victor Turner of the University of Chicago.

European

 * Greek mythology
 * Adonis
 * Dionysus, in one myth, he was torn apart by Titans, but brought back to life
 * Hecate, goddess of magic and crossroads
 * Hermes, god of roads, merchants, travelers, trade, thievery/thieves, cunning, and animal husbandry; messenger of Zeus and psychopomp
 * Iris, goddess of the rainbow and messenger of Hera, could travel to Hades and return
 * Persephone, is technically a liminal deity due to spending part of her time in the underworld and the rest above ground, is often seen as a goddess of spring and new growth
 * Roman mythology
 * Bacchus, Roman name for Dionysus
 * Cardea, goddess of health, thresholds, and door hinges and handles
 * Forculus, Lima, and Limentinus, minor deities of thresholds or doorways; see indigitamenta
 * Janus, dual-faced god of gates, doors, doorways, beginnings and endings, for whom January is named
 * Mercury, messenger god and psychopomp; equivalent to the Greek Hermes and shares several of his functions, such as being a god of commerce, travelers, merchants, and thieves
 * Portunus, god of keys, doors, and livestock
 * Proserpina, Roman equivalent of Persephone who spent some of her time living in the world of the dead
 * Terminus, god who protected boundary markers
 * Trivia, goddess of magic and the three-way crossroads; equivalent to the Greek Hecate
 * Norse mythology
 * Gná, Frigg's personal messenger; she rode the horse Hofvarpnir who could travel over both sea and sky
 * Hermóðr, messenger of the Norse gods; he rode to Hel to plead for Baldr's return. It was ultimately unsuccessful.
 * Óðinn, god of wisdom, war and death, among other things; he is described as at least once visiting the underworld on Sleipnir, raising a volva to interrogate, and visiting Jǫtunn on three separate occasions in their domain in order to gather more wisdom. Norse equivalent of Hermes.
 * Baltic mythology
 * Užsparinė, Lithuanian goddess of land borders
 * Óðinn, god of wisdom, war and death, among other things; he is described as at least once visiting the underworld on Sleipnir, raising a volva to interrogate, and visiting Jǫtunn on three separate occasions in their domain in order to gather more wisdom. Norse equivalent of Hermes.
 * Baltic mythology
 * Užsparinė, Lithuanian goddess of land borders
 * Užsparinė, Lithuanian goddess of land borders

Asian religions

 * Chinese mythology
 * Chen Huang Shen, the god of walls and moats
 * Men Shen, the gods of doors
 * Chen Wenlong, god of city walls in Fuzhou
 * Fan Zeng, god of city walls in Hezhou and He county
 * Guan Ying, god of city walls in Longxing, Gan, Yuan, Jiang, Ji, Jianchang, Linjiang, Nanchang, and Nankang
 * Huang Xie, god of city walls in Suzhou
 * Huo Guang, Yu Bo, and Chen Huacheng; gods of city walls in Shanghai
 * Ji Shun, god of city walls in Zhengzhou, Zhenjiang, Qingyuan, Ningguo, Taiping, Xiangyang, Xingyuan, Fuzhou, Nanan, and Huating
 * Jian Yi, god of city walls in Tanghongzhou
 * Jiao Ming, god of city walls in Ezhou
 * Liu Zhongyuan, god of city walls in Liuzhou
 * Pang Yu, god of city walls in Xiaoxing
 * Qu Tan, god of city walls in Taizhou
 * Shen Sheng, god of city walls in Wuzhou
 * Su Jian, god of city walls in Yongzhou
 * Te Xuan, god of city walls in Jinan
 * Wen Tianxiang, god of city walls in Huangzhou
 * Xiao He, god of city walls in Gu
 * Yang Jianshan, god of city walls in Beijing
 * Yao Yichung, god of city walls in Xingguojun
 * Ying Bu, god of city walls in Zhenzhou and Liuhe
 * Ying Zhixu, god of city walls in Yunzhou
 * Zhou Ke, god of city walls in Jiangyin
 * Zhu Yigui, god of city walls in Xiaonanmen
 * Korean mythology
 * Jangseung, a totem pole traditionally placed at the edges of villages to mark for village boundaries and frighten away demons; also worshipped as tutelary deities
 * Munshin, Korean deity of the door. He was considered one of the most powerful of the house gods (Gashin), especially in Jeju Island.
 * Shinto
 * Izanagi, creator god who descended into Yomi to bring back his wife, only to be repulsed at how hideous she had become, run away, and seal the entrance to Yomi with a rock
 * Izanami, creator goddess who died, but could not leave Yomi and thus became queen of the underworld and the dead
 * Hindu mythology
 * Agni, god of fire and messenger between gods and mortals, Ganesha seems to have at least partially taken over this role in modern Hinduism
 * Ganesha, remover of obstacles, a messenger of the gods and goddesses who must be propitiated before any of the other deities
 * Pushan, solar deity and psychopomp responsible for marriages, journeys, roads, the feeding of cattle, and overseeing the journey of the dead to the afterlife
 * Mesopotamian mythology
 * Dumuzi/Tammuz
 * Inanna/Ishtar
 * Phrygian mythology
 * Attis
 * Mesopotamian mythology
 * Dumuzi/Tammuz
 * Inanna/Ishtar
 * Phrygian mythology
 * Attis
 * Attis

African and American religions

 * African religion
 * Osiris, ancient Egyptian god who was murdered, but was reassembled and brought back to life by his wife Isis, but was still confined to the underworld and became the ruler of it
 * Legba, phallic crossroad spirit and trickster in West African Vodun, he is the bringer of magic, master diviner and speaker of every language who facilitates communication between man and the gods. Legba is also the remover of obstacles and the guardian of the home and crossroads.
 * Afro-American religion
 * Ellegua, the messenger god and psychopomp in Santería, Louisiana Voodoo, Haitian Voodoo, and Candomblé
 * Afro-American religion
 * Ellegua, the messenger god and psychopomp in Santería, Louisiana Voodoo, Haitian Voodoo, and Candomblé