The mythology or religion of most cultures incorporate a god of death or, more frequently, a divine being closely associated with death, an afterlife, or an underworld. They are often amongst the most powerful and important entities in a given tradition, reflecting the fact that death, like birth, is central to the human experience. In religions where a single god is the primary object of worship, the representation of death is usually that god's antagonist, and the struggle between the two is central to the folklore of the culture. In such dualistic models, the primary deity usually represents good, and the death god embodies evil. Similarly, death worship is used as a derogatory term to accuse certain groups of morally abhorrent practices which set no value on human life. In monotheistic religions, death is commonly personified by an angel or demon standing in opposition to the god.
In polytheistic religions which have a complex system of deities governing various natural phenomena and aspects of human life, it is common to have a deity who is assigned the function of presiding over death. This deity may actually take the life of humans or, more commonly, simply rule over the afterlife in that particular belief system (a single religion may have separate deities performing both tasks). The deity in question may be good, evil, or neutral and simply doing their job, in sharp contrast to a lot of modern portrayals of death deities as all being inherently evil just because death is feared. Hades from Greek mythology is an especially common target. The inclusion of such a "departmental" deity of death in a religion's pantheon is not necessarily the same thing as the glorification of death.
A death deity has a good chance of being either male or female, unlike some functions that seem to steer towards one gender in particular, such as fertility and earth deities being female and storm deities being male. A single religion/mythology may have death gods of more than one gender existing at the same time and they may be envisioned as a married couple ruling over the afterlife together, as with the Aztecs, Greeks, and Romans.
In monotheistic religions, the one god governs both life and death (as well as everything else). However, in practice this manifests in different rituals and traditions and varies according to a number of factors including geography, politics, traditions, and the influence of other religions.
Ossetian
Emperor(s) of Youdu (Capital City of the Underworld)
Judges of the Ten Underworld Courts
The rest only have surnames including Li, Yu, Lu, Bi, Lu and Xue.
Four Kings of the Underworld
Ghost Kings of the Five Regions
Ghost Kings of the Five Regions (Ver.2)
Governors of Fengdu
Imperial Censor of Fengdu
Four Generals of the Direct Altar of Fengdu
Eight Generals of the Inner Altar of Fengdu
Eight Generals of the Outer Altar of Fengdu
Ten Masters of the Underworld
(Note: in some versions, Xie Bi'an and Fanjiu are the Bai Wuchang and Hei Wuchang, respectively.)
Four Strongmen of Fengdu
Two Agents of Fengdu
Wardens of the Nine Prison of Fengdu
Administers of the Six Paths of Rebirth of Fengdu
Judges of Fengdu
Yama - the god of death & divine judge of afterlife
Chitragupta - Yama's record keeper, keeps account of the good & misdeeds of souls, on the basis of which the dead are judged.
Yamaduta - Spirits under control of Yama, who are responsible for bringing the dead souls into Yama's presence. However, from the anecdote of Satyavan & Savitri, it is shown that even Yama performs this role.
Kāla - the personification of time, also associated with death
Shiva - the god who is the destroyer of the world at the time of pralaya. As Kalantaka, he is also the conqueror of death. As Bhairava, he is strongly associated with death & destruction.
Kali - Shiva's spouse, strongly associated with death & destruction.
Chamunda - A related form of Kali, invoked for seeking death of enemies during wartime.
Tibetan Buddhism, like all other Buddhist denominations, affirms the rejection of the existence of souls (anatta) & existence of a creator God (see the theory of dependent origination), while at the same time affirming in the existence of heaven and hell. The beings listed here aren't 'gods of death' in the traditional sense, they are rather beings that invoke a lot of funerary aspect with them.
Citipati - guardian spirits of charnel grounds
Dakini - Female spirits strongly associated with the imagery of death.
Heruka - Beings strongly associated with the imagery of death & charnel grounds
Wrathful deities - Meditational deities invoking the imagery of death.
Gede lwa