The name Cassiopeia is a girl's name of Greek origin. Cassiopeia and is often added to lists like Unique Girl Names: Unusual and Rare and discussed in our forums with posts like "Which would you choose?".
From the experts:
Cassiopeia, the name of a mythological mother who became a stellar constellation, is challenging but intriguing, and has all those softening Cass nicknames available. With the rise of other otherworldly and mythical choices, from Apollo to Jupiter to Juno, Cassiopeia may just feel more possible for mortals now than ever before in its long history.