The Nirgul tablet (also known as Cerberus relief) was a Parthian relief carving of the Mesopotamian god Nergal, a three-headed dog and a seated female figure:
According to Wikipedia, which cites Lucinda Dirven's paper A Goddess with dogs from Hatra, the seated female figure may be the pre-Islamic Arabian goddess Al-Lat:
The tablet was recovered from a room in the First Temple at the site where it had been encased in a wall. Alongside the figure of Nirgul, a seated female figure is thought to depict the goddess Al-Lat.
Source: Wikipedia contributors. (2019, April 28). Nirgul tablet. In Wikipedia, The Free Encyclopedia. Retrieved 23:22, September 16, 2019, from https://en.wikipedia.org/w/index.php?title=Nirgul_tablet&oldid=894533315
Encyclopaedia Iranica, on the other hand, tells us the goddess is probably the Syrian Atargatis:
The so called “Cerberus relief” shows a god, his consort, and a three headed dog. The god stands frontally, clad in Parthian dress somewhat like that worn by the bronze figure from Šāmī; an eagle perches on his horned diadem (which surely recalls the earlier Mesopotamian horned crown), and snakes spring from his waist and shoulders. In his upraised right hand he holds an axe; in his left, a sword and the leash of the dog. While the triple headed dog is clearly based on the Greek Cerberus, here he identifies the god as the underworld god Nergal. His consort, seated frontally on a throne flanked by griffins, is crowned by an eagle. In her right hand she holds a feather; in her left, the standard, an important Hatran religious symbol. Her footstool is decorated with fish. The standard, the eagle, and the fish probably identify her as Atargatis, the goddess of the Syrian city of Hierapolis. Additional animal attributes are associated with these and other Semitic deities (H. Ingholt, “Parthian Sculptures from Hatra,” Memoirs of the Connecticut Academy of Arts and Sciences 12, New Haven, 1954, pp. 17 33; Ghirshman, Persian Art, p. 87, fig. 98).
There's also Ereshkigal, Nergal's consort.
Which one is the more likely candidate, and why? Are there other candidates?