Omicron Cassiopeiae (ο Cas, ο Cassiopeiae) is a triple star system in the constellation Cassiopeia. It is approximately 910 light years from Earth.
The primary component, ο Cassiopeiae A, is a blue-white B-type giant with a mean apparent magnitude of +4.54. It is classified as a Gamma Cassiopeiae type variable star and its brightness varies from magnitude +4.50 to +4.62. The primary is a spectroscopic binary, and its close companion completes one orbit every 2.83 years. A more distant companion, ο Cassiopeiae B, lies 33.6 arcseconds away. It is an eleventh magnitude, yellow-white F-type main sequence dwarf.