» For the opera by Francesco Cavalli, see Egisto In Greek mythology, Aegisthus (Ancient Greek: Αίγισθος, "goat strength" — also transliterated as Aegisthos or Aigísthos) was the son of Thyestes and of his daughter, Pelopia. Thyestes felt he'd been deprived of the Mycenean throne unfairly by his brother, Atreus. The two battled back and forth several times. In addition, Thyestes had an affair with Atreus' wife, Aerope. In reven… (More on Aegistheus)