Cassiopeia can refer to:

• Cassiopeia (mythology) (or Casseipeia), a queen of Aethiopia in Greek mythology. See also Boast of Cassiopeia.
• Cassiopeia (constellation), a northern constellation representing the queen.
• Cassiopeia A, a galaxy in that constellation.
• Cassiopea, the genus of the "upside-down" jellyfish
• Cassiopeia Train, an overnight rail service in Japan.
• Cassiopea (Encantadia), the first Queen of Lireo in the Encantadia fantasy series of GMA Network.
• Casio Cassiopeia, a series of pocket PCs.
• Casiopea, a Japanese jazz fusion group.
• Cassiopeia (Battlestar Galactica), a TV character from Battlestar Galactica.
• Cassiopeia, a tortoise featured in Michael Ende's fantasy book Momo

Cassiopeia | Cassiopeia | Kasjopeja | Cassiopéia | Кассиопея | Cassiopeia