9th-century Byzantine nuns

Kassia, Cassia, Kassiane, or Kassiani (, ; – c.865) was a Byzantine-Greek composer, hymnographer and poet. She holds a unique place in Byzantine music as the only known woman whose music appears in the Byzantine liturgy. Approximately fifty of her hymns are extant, most of which are stichera, though at least 26 have uncertain attribution. The authenticity issues are due to many hymns being anonymous, and others ascribed to different authors in different manuscripts. She was an abbess of a convent in the west of Constantinople.

daughter of Theophilos