Chemosh was the god of the Moabites. He is most notably attested in the Mesha Stele and the Hebrew Bible. While he is most readily associated with the Moabites, according to Judges 11:23-24 he seems to have been the national deity of the Ammonites as well.
Etymology
The etymology of "Chemosh" is unknown, although it is believed to be related to the Semitic god Shamash. However, given that he is also known from Ebla as Kamish, it is also speculated he might be a form of the Mesopotamian deityNergal.
According to the Hebrew Bible, the worship of this god, "the abomination of Moab," was introduced at Jerusalem by Solomon, but was abolished by Josiah. On the Moabite stone, Mesha ascribed his victories over the king of Israel to this god, "and Chemosh drove him out from before me." According to Morris Jastrow, Jr. and George Aaron Barton in the Jewish Encyclopedia, The name of the father of Mesha, Chemosh-melek, indicates the possibility that Chemosh and Malik were one and the same deity. Book of Judges 11:24 has been thought by some to be a proof of this, since it speaks of Chemosh as the god of the Ammonites, while Moloch is elsewhere their god. Solomon is said to have built a sanctuary to Chemosh on the Mount of Olives, which was maintained till the reform of Josiah. This movement by Solomon was no doubt to some extent a political one, but it made the worship of Chemosh a part of the religious life of Israel for nearly 400 years.
Next CHEMOS, th' obscene dread of MOABS Sons, From AROER to NEBO, and the wild Of Southmost ABARIM; in HESEBON And HERONAIM, SEONS Realm, beyond The flowry Dale of SIBMA clad with Vines, And ELEALE to th' ASPHALTICK Pool. PEOR his other Name, when he entic'd ISRAEL in SITTIM on their march from NILE To do him wanton rites, which cost them woe. Yet thence his lustful Orgies he enlarg'd Even to that Hill of scandal , by the Grove Of MOLOCH homicide, lust hard by hate; Till good JOSIAH drove them thence to Hell.
Harry Turtledove's short alternate history story "Occupation Duty" features a society where Chemoshism survived to the present day, and the popular image of Chemosh has apparently metamorphosed into something akin to Yahweh.