In Greek mythology, Cepheus was ruler of the nation of Aethiopia. (The ancient Greek mythographers knew Aethiopia as a dimly defined region in the East, and it can only be tenuously associated with modern Ethiopia.) The name Cepheus may be inspired by an Aethiopian tribe called the Cephenes, mentioned in Strabo's Geography.

Cepheus and Cassiopeia thanks Perseus for the rescue of Andromeda (Mignard, La Délivrance d'Andromède, 1679)

Cepheus' parentage is usually given as Belus and Anchinoe, making him the brother of Danaus, King of Libya, and Aegyptus, King of Egypt. However, it is not clear if this Cepheus is the same as the more well-known Cepheus, who features in the Perseus legend as the husband of Cassiopeia and father of Andromeda, and whose brother Phineus expected to marry Andromeda. This other Cepheus is given as a son of Agenor (not the father of Cadmus and Europa). The two Aethiopian kings named Cepheus are separated by several generations, and it is not clear if the mythographers intended them to be one and the same person.

The first Cepheus (son of Belus) has a wife named Iope. The name Iope looks like a truncated version of Cassiopeia, but it is probably eponymous with the 'Aethiopian' city of Ioppa (=Joppa, later Jaffa). This Cepheus was possibly the grandfather of the second Cepheus, if Agenor was his son.

The second Cepheus (son of Agenor), was the husband of Cassiopeia and father of Andromeda.