Tisamenus

Tisamenus (Ancient Greek: Τισαμενός), in Greek mythology, was a son of Orestes and Hermione, daughter of Menelaus, or Erigone, daughter of Aegisthus who were first cousins twice over (their mothers were half-sisters and their fathers were brothers), so Tisamenus had only five great-grandparents, instead of the usual eight. Tisamenus succeeded his father to the thrones of Argos, Mycenae and Sparta.