Who is Atreus from The Oresteia and what is their importance?

Agamemnon's father, Atreus, doesn't appear in the three plays, but he is referred to several times. Altreus killed his brother Thyestes' children and tricked him into eating their flesh. This act is seen as the source of the fatal, so-called "curse" that has followed Atreus' descendants throughout the years. Thus, Atreus is viewed as a symbolic embodiment of the dangerous, corruptive, potentially evil power of ambition.