Cassiopeia (mother of Andromeda)

[3] Cassiopeia boasted that she (or her daughter Andromeda), was more beautiful than all the Nereids, the nymph-daughters of the sea god Nereus.

[4] Accounts differ as to whether Poseidon decided to flood the whole country[5] or direct the sea monster Cetus to destroy it.

In either case, trying to save their kingdom, Cepheus and Cassiopeia consulted a wise oracle, who told them that the only way to appease the sea gods was to sacrifice their daughter.

[5] Poseidon thought Cassiopeia should not escape punishment, so he placed her in the heavens chained to a throne in a position that referenced Andromeda's ordeal.

The constellation is also visible in countries north of the Tropic of Capricorn, in late spring.

Poseidon's punishment: Cassiopeia as a constellation sitting in the heavens tied to a chair. Hyginus, Poeticon Astronomicon . "U.S. Naval Observatory Library"
The king of Ethiopia Cepheus and the queen Cassiopeia thank Perseus for freeing their daughter Andromeda, La Délivrance d'Andromède (1679) Pierre Mignard , Louvre