Ancient Mesopotamian underworld in the context of "Gilgamesh"

Sin (/ˈsiːn/) or Suen (Akkadian: 𒀭𒂗𒍪, EN.ZU) also known as Nanna (Sumerian: 𒀭𒋀𒆠 ŠEŠ.KI, NANNA) is the Mesopotamian god representing the moon. While these two names originate in two different languages, respectively Akkadian and Sumerian, they were already used interchangeably to refer to one deity in the Early Dynastic period. They were sometimes combined into the double name Nanna-Suen. A third well attested name is Dilimbabbar (𒀭𒀸𒁽𒌓). Additionally, the name of the moon god could be represented by logograms reflecting his lunar character, such as 30 (𒀭𒌍), referring to days in the lunar month or U₄.SAKAR (𒀭𒌓𒊬), derived from a term referring to the crescent. In addition to his astral role, Sin was also closely associated with cattle herding. Furthermore, there is some evidence that he could serve as a judge of the dead in the underworld. A distinct tradition in which he was regarded either as a god of equal status as the usual heads of the Mesopotamian pantheon, Enlil and Anu, or as a king of the gods in his own right, is also attested, though it only had limited recognition. In Mesopotamian art, his symbol was the crescent. When depicted anthropomorphically, he typically either wore headwear decorated with it or held a staff topped with it, though on kudurru the crescent alone serves as a representation of him. He was also associated with boats.

The goddess Ningal was regarded as Sin's wife. Their best attested children are Inanna (Ishtar) and Utu (Shamash), though other deities, for example Ningublaga or Numushda, could be regarded as members of their family too. Sin was also believed to have an attendant deity (sukkal), Alammuš, and various courtiers, such as Nineigara, Ninurima and Nimintabba. He was also associated with other lunar gods, such as Hurrian Kušuḫ or Ugaritic Yarikh.

Shamash (Akkadian: šamaš), also known as Utu (Sumerian: utu 𒀭𒌓 "Sun"), was the ancient Mesopotamian sun god. He was believed to see everything that happened in the world every day, and was therefore responsible for justice and protection of travelers. As a divine judge, he could be associated with the underworld. Additionally, he could serve as the god of divination, typically alongside the weather god Adad. While he was universally regarded as one of the primary gods, he was particularly venerated in Sippar and Larsa. The moon god Nanna (Sin) and his wife Ningal were regarded as his parents, while his twin sister was Inanna (Ishtar). Occasionally other goddesses, such as Manzat and Pinikir, could be regarded as his sisters too. The dawn goddess Aya (Sherida) was his wife, and multiple texts describe their daily reunions taking place on a mountain where the sun was believed to set. Among their children were Kittum, the personification of truth, dream deities such as Mamu, as well as the god Ishum. Utu's name could be used to write the names of many foreign solar deities logographically. The connection between him and the Hurrian solar god Shimige is particularly well attested, and the latter could be associated with Aya as well.

While no myths focusing on Utu are known, he often appears as an ally of other figures in both Sumerian and Akkadian compositions. According to narratives about Dumuzi's death, he helped protect him when the galla demons tried to drag him to the underworld. In various versions of the Epic of Gilgamesh and in earlier Gilgamesh myths, he helps this hero defeat the monstrous Humbaba. In the myth Inanna and An, he helps his sister acquire the temple Eanna. In How Grain Came to Sumer, he is invoked to advise Ninazu and Ninmada.

Ningishzida (Sumerian: 𒀭𒊩𒌆𒄑𒍣𒁕 NIN.G̃IŠ.ZID.DA, possible meaning "Lord [of the] Good Tree") was a Mesopotamian deity of vegetation, the underworld and sometimes war. He was commonly associated with snakes. Like Dumuzi, he was believed to spend a part of the year in the land of the dead. He also shared many of his functions with his father Ninazu.

In myths he usually appears in an underworld setting, though in the myth of Adapa he is instead described as one of the doorkeepers of the sky god Anu.

Ninisina (Sumerian: "Mistress of Isin") was a Mesopotamian goddess who served as the tutelary deity of the city of Isin. She was considered a healing deity. She was believed to be skilled in the medical arts, and could be described as a divine physician or midwife. As an extension of her medical role, she was also believed to be capable of expelling various demons. Her symbols included dogs, commonly associated with healing goddesses in Mesopotamia, as well as tools and garments associated with practitioners of medicine.

While Ninisina was initially considered to be an unmarried and childless goddess, the god Pabilsag eventually came to be viewed as her husband. Her children were Damu and Gunura, like her considered to be healing deities, as well as Šumaḫ, who also served as her sukkal, a type of divine attendant. Further members of her court included Ninarali, a goddess associated with the underworld, harpist goddesses Ninigizibara and Ninḫinuna, and sometimes Ninshubur. Ninisina also developed associations with various other goddesses of similar character, including Ninkarrak, Gula and Nintinugga. However, while they were often considered analogous, they originated in different areas of Mesopotamia and their individual traits differed. A further goddess connected with her was Bau, who might have developed into a healing goddess because of the association between them. For political reasons, Ninisina also acquired some traits originally belonging to Inanna when the kings of Isin lost control over the cult center of the latter goddess, Uruk.

Lugal-irra (𒀭𒈗𒄊𒊏) and Meslamta-ea (𒀭𒈩𒇴𒋫𒌓𒁺𒀀) were a pair of Mesopotamian gods who typically appear together in cuneiform texts and were described as the "divine twins" (Maštabba). They were regarded as warrior gods and as protectors of doors, possibly due to their role as the gatekeepers of the underworld. In Mesopotamian astronomy they came to be associated with a pair of stars known as the "Great Twins", Alpha Geminorum and Beta Geminorum. They were both closely associated with Nergal, and could be either regarded as members of his court or equated with him. Their cult centers were Kisiga and Dūrum. While no major sanctuaries dedicated to them are attested elsewhere, they were nonetheless worshiped in multiple other cities.

Nergal (Sumerian: 𒀭𒄊𒀕𒃲 KIŠ.UNU or GÌR.UNU.GAL; Hebrew: נֵרְגַל, Modern: Nerəgal, Tiberian: Nērəgal; Aramaic: ܢܸܪܓܲܠ; Latin: Nirgal) was a Mesopotamian god worshiped through all periods of Mesopotamian history, from Early Dynastic to Neo-Babylonian times, with a few attestations indicating that his cult survived into the period of Achaemenid domination. He was primarily associated with war, death, and disease, and has been described as the "god of inflicted death". He reigned over Kur, the Mesopotamian underworld, depending on the myth either on behalf of his parents Enlil and Ninlil, or in later periods as a result of his marriage with the goddess Ereshkigal. Originally either Mammitum, a goddess possibly connected to frost, or Laṣ, sometimes assumed to be a minor medicine goddess, were regarded as his wife, though other traditions existed, too.

His primary cult center was Kutha, located in the north of historical Babylonia. His main temple bore the ceremonial name E-Meslam and he was also known by the name Meslamtaea, "he who comes out of Meslam". Initially he was only worshiped in the north, with a notable exception being Girsu during the reign of Gudea of Lagash, but starting with the Ur III period he became a major deity in the south too. He remained prominent in both Babylonia and Assyria in later periods, and in the Neo-Babylonian state pantheon he was regarded as the third most important god, after Marduk and Nabu.