Beelzebub, a translation of Baal-zebub. Both translate to Lord of Flies (more commonly), or Lord of the Dungheap. Because flies often gather around decaying corpses and as well spread disease, the term is symbolic for Lord of Death, Decay, Disease, etc. Beelzebub is either used as a synonym for Satan himself, or, as was made popular in Paradise Lost, as Satan's second-in-command devil.
You cast out devils by Beelzebub, chief of devils. (Accusation made toward Jesus, meaning he casts out devils by calling upon Satan.)