Belus (Greek Βῆλος) the Egyptian is in Greek Mythology a son of Poseidon by Libya. He was a King of Egypt and father of Aegyptus and Danaus and (usually) brother to Agenor.
Apollodorus claims that Aegyptus and Danaus were twins and that their mother was Achiroe, daughter of the river-god Nilus. He says that it was Euripides who added Cepheus and Phineus as additional sons of Belus. Belus ruled in Egypt, and Agenor ruled over Sidon and Tyre in Phoenicia. Aegyptus ruled over Egypt and Arabia, and Danaus ruled over Libya. Apollodorus also claims that Agenor was Belus' twin brother.
According to Pherycides (3F21) Belus also had daughter named Damno who married her uncle (Belus' brother) Agenor and bore to him Phoenix and two daughters named Isaie, and Melia, these becoming wives respectively to their cousins Aegyptus and Danaus sons of Belus.
In the Eoiae (see Hesiod) Belus was also the father of a daughter named Thronia on whom Hermaon, that is Hermes, fathered Arabus, presumably the eponym of Arabia.
Some sources make Belus father of the Lamia.
Nonnus (Dionysiaca 3.287f) makes Belus the father of "as many as five", namely Phineus, Phoenix, Agenor (identified as the father of Cadmus), Aegyptus, and Danaus, though Nonnus elsewhere (2.686) makes Phineus to be Cadmus' brother. Nonnus has Cadmus identify Belus as "the Libyan Zeus" and refer to the "new voice of Zeus Asbystes", meaning the oracle of Zeus Ammon at Asbystes. (Is the god Ba‘al Hammon of Carthage part of this mix?)
Modern writers speculate on a possible connection between Belus and one or another god who bore the common northwest Semitic title Ba‘al.