In Greek mythology, the name of three different people:
- The son of the King Belus (1) of Ethiopia. He is the husband of Cassiopeia and father of Andromeda. His wife boasted that she, or her daughter, were more beautiful than the Nereids and in revenge Poseidon sent a sea monster to plague his lands. He consulted the oracle of Ammon and was told that the problem would end if he exposed his daughter as prey for the monster. His people forced him to comply with the oracle, and he chained Andromeda to a rock by the sea. She was rescued by Perseus who killed the monster and married the girl.
After his death Cepheus was placed among the stars.
- A son of Aleus and Naeara (or Cleobule). He succeeded his father as the ruler of Tegea in Arcadia. Cepheus was the father of twenty sons and two daughters, but nearly all of his sons perished in an expedition they undertook with Heracles. He was one of the Argonauts and is the reputed founder of Caphyae (Bibliotheke I, 9.16; II, 7.3; III, 9.1; Argonautica I, 161; Fabulae 14; Guide to Greece VIII, 8.3, 23.3).
- One of the participants in the Calydonian Hunt.