Belus (Greek: Βῆλος, Bē̂los) was in Greek mythology a king of Egypt and father of Aegyptus and Danaus and (usually) brother to Agenor. The wife of Belus has been named as Achiroe, or Side (eponym of the Phoenician city of Sidon).
Diodorus Siculus claims that Belus founded a colony on the river Euphrates, and appointed the priests-astrologers whom the Babylonians call Chaldeans who like the priests of Egypt are exempt from taxation and other service to the state.
Belus was the son of Poseidon and Libya. Maybe he is also Busiris, son of Libya, ruler of Egypt, killed by Heracles, although Heracles was born many generations after Belus since he was a grandchild of Perseus; see Argive genealogy below. According to Pausanias, Belus founded a temple of Heracles in Babylon.
The Bibliotheca also claims that Agenor was Belus' twin brother. Belus ruled in Egypt, and Agenor ruled over Sidon and Tyre in Phoenicia. The wife of Belus has been named as Achiroe, allegedly daughter of the river-god Nilus. Her sons Aegyptus and Danaus were twins. Later Aegyptus ruled over Egypt and Arabia, and Danaus ruled over Libya. Pseudo-Apollodorus says that it was Euripides who added Cepheus and Phineus as additional sons of Belus.