Let's see what my copy of The Concise Mythological Dictionary has to say- it's a great little book, well worth getting.
Here are various references to where other mythologies were spun into Christian mythology, In general, a number of the deities of "pagan" religions contemporary to early Christianity were demonized to discourage their worship. I've included some good ones as well as the demonizing ones.
Asmodeus - Latinized form of the Hebrew Ashmedai, prince of demons in medieval Jewish legend.
Beelzebub - the term is a deliberate mocking perversion of the Canaanite Baal-Zebul, 'Prince Baal' one of the standard titles by which Baal was called. Baal was a fertility god in Canaanite (Syro-Palestinian) myth, with attributes of lightning, the rainstorm, and the generative forces of nature.
Cherubim - a lesser order of ancient Mesopotamian deities: bulls with wings and human heads who guarded the royal palace gates. They are mentioned in Ezekiel in the bible as bearing the throne and chariot of God, and later were conceived as a type of angel.
Daemon - a Greek term originally denoting the deities in general, but later used for intermediate or lesser gods, and protective spirits. Under the influence of medieval Christianity the word became known as referring to evil spirits.
Demiurge (Demiourgos): in the dualistic Gnostic theology, the creator of the material world, which is evil by nature. Hence he was identified by the early Christian Gnostic heretics with Yahweh.
Demogorgon - a confused medieval rendering of Demiurge.
Easte (Ostara) - ancient Saxon goddess of spring, associated with fertility of the earth, from whose name and rites the festival of Easter is derived.
Gehennna - a corruption of the Hebrew "Genem Hinnom", originally a place outside Jerusalem where the Canaanites performed human sacrifices and in later Israelite times became a refuse heap. As a result it was used allegorically for punishment of the wicked in the afterlife - hell.
Lilith - a night demoness of ancient Assyria, mentioned in the old testament and adopted into medieval Judeo-Christian demonology as a sort of lamia.
Lucifer - the "light bearer" (Phosphoros in the Greek) the name given to the planet Venus as the morning star and called the son of Eos as a personified deity. (Eos was the Greek goddess of the dawn.) In medieval Christian theology the name was applied to the chief of the angels who rebelled and was cast down into hell - Satan.
Marduk - chief god of ancient Babylon, who slew Tiamat, and became king of gods. He is the Merodach of the old testament and his name is also reflected in that of Mordecai.
Sabazios - a deity originating in Phrygian Asia Minor, often identified with Dionysus and Zeus. His cult spread during the Roman Empire, and he was identified by some with Yahweh Sabaoth of the old testament.
Seraphim - possibly they were originally winged serpents. The word means the fiery or burnings ones in Hebrew. Divine winged creatures associated with the Cherubim in the old testament and later taken to be angels.
Teraphim - the little images of ancient Syrian household gods mentioned in the old testament in connection with the story of Rachel. They probably correspond to the Roman Lares (ancestral spirits among the household gods) and Penates (household gods who were the protective family deities).
Tiamat - primeval Sumero-Babylonian goddess personifying the salt water ocean and waters of chaos. Described as a huge, bloated dragon monster, whose consort is Apsu, (the abyss of sweet waters under the earth, whereas Tiamat is the abyss of salt waters). Marduk split her body in two, fixing one half on high to become the watery vault of the heavens. "The deep" (Hebrew tehom) at the beginning of Genesis derives from Tiamat.
In general, I find the origins and intertwining of mythology fascinating. The Concise Mythological Dictionary has more detail which I skipped over.
Orcus was the Roman name of Hades. I think we covered that in an earlier thread.
