In Greek mythology , the wife of Perseus .
She was the daughter of King Cepheus and Queen Cassiope of Joppa in Palestine (called Ethiopia). Her mother boasted that Andromeda was more beautiful than the Poseidon punished her by sending a sea monster to devastate Joppa. To appease the gods, Andromeda was chained to a rock and left to be devoured by the monster. Perseus flew by on Pegasus , fell in love with Andromeda, and slew the monster. She married him and bore him six sons and a daughter. After her death she became a constellation.