This paper examines how the character of Cassandra in the ancient drama "Agamemnon", first in the Oresteia trilogy written
by the Greek playwright Aeschylus, initially may seem relevant only as a secondary character who appears in a minor scene. It attempts to show how Cassandra provides very necessary, crucial elements to the plot and dramatic action which help to portray Aeschylus' messages concerning justice and vengeance. It also looks at how one of the most important aspects of Cassandra's character is her unique style of prophetic vision, which allows her to foresee the past, present and future, yet denies her the luxury of actually being believed in her predictions.