Atropos or Aisa was the oldest of the Three Fates, and was known as the "inflexible" or "inevitable." It was Atropos who chose the mechanism of death and ended the life of each mortal by cutting their thread with her "abhorred shears." She worked along with her two sisters, Clotho, who spun the thread, and Lachesis, who measured the length. Atropos has been featured in several stories such as Atalanta and Achilles.
Her origin, along with the other two fates, is uncertain, although some called them the daughters of the night. It is clear, however, that at a certain period they ceased to be only concerned with death and also became those powers who decided what may happen to individuals. Although Zeus was the chief Greek god and their father, he was still subject to the decisions of the Fates, and thus the executor of destiny, rather than its source. According to Hesiod's Theogony, Atropos and her sisters (Clotho and Lachesis) were the daughters of Nyx (Night), though later in the same work (ll. 901-906) they are said to have been born of Zeus and Themis.