The constellation named after the mythological king Cepheus is Cepheus.
Cepheus is a northern constellation named for Cepheus, the king of Aethiopia in Greek mythology. He is best known as the husband of Cassiopeia and the father of Andromeda. Their family appears together in the sky, alongside Perseus, the hero who rescued Andromeda, and Cetus, the sea monster associated with her story.
Cepheus was included among the 48 constellations recorded by Ptolemy in the 2nd century and is still one of the 88 official modern constellations. It lies near the north celestial pole, so much of it is circumpolar from northern latitudes.
The constellation is commonly drawn as a roughly house-shaped or throne-like figure, reflecting its royal identity. Its brightest star is Alderamin, or Alpha Cephei. Cepheus is sometimes confused with Cassiopeia because both belong to the same mythological family, but Cassiopeia represents the king’s wife, not the king himself.