He is mentioned by Rev. Hoadley in his sermon against the close presence of Satan in Dunwich shortly before he disappeared.

The Phoenician god Beelzebub was the patron of the Philistines in ancient Palestine. Said to be the son of El or of Dagon in the attributes of El. He is also identified with the god of Ekron, Baal-Zebub. The term is a deliberate mocking perversion of the Canaanite Baal-Zebul ("Prince Baal"), one of the standard titles of the god Baal. He is also called 'Lord of the Flies', derived from the Hebrew "Baal-Zevuv". Later, he was demegrated into a biblical demon. In Hebrew mythology, the Devil. In the New Testament he seems to be synonymous with Satan (e.g., Matthew 12:24-27). In Milton's Paradise Lost, the chief of the fallen angels, next to Satan in power. [Late Latin, from Greek Beelzeboub, from Hebrew ba al zebub, also ba al zevuv, or "lord of flies," god of the Ekronites (II Kings 1:2) : ba al, lord + zebub, fly.]

[The Dunwich Horror - H.P.L.]
[The Shadow Over Innsmouth - H.P.L.]