In Greek mythology, Anaxo (Ancient Greek Ἀναξώ) daughter of Alcaeus (son of Perseus) marries her uncle Electryon, king of Mycenae, and becomes mother of Alcmena and of the nine legitimate sons who fall fighting the Taphians. Through Alcmena she is grandmother of Heracles. Distinct from the Troezenian girl of the same name abducted by Theseus.
Adapted from Wikipedia, "Anaxo (daughter of Alcaeus)" · CC BY-SA 4.0
I.Wife of Electryon
Apollodorus (Bibliotheca 2.4.5) makes Anaxo daughter of Alcaeus by Astydamia (or Laonome, or Hipponome in variants) and sister of Amphitryon. Electryon marries her — his brother's daughter — and by her has Alcmena and nine sons: Stratobates, Gorgophonus, Phylonomus, Celaeneus, Amphimachus, Lysinomus, Chirimachus, Anactor, and Archelaus.
When the Taphians raid Electryon's cattle, all nine legitimate sons die in the counter-attack; only the bastard Licymnius survives among the king's male children. Alcmena later marries Amphitryon, so Alcaeus stands as father of one parent and grandfather of the other in Heracles' birth-saga.
II.Homonym care
The atlas id anaxo-alcaeus is Alcaeus' Mycenaean daughter alone. Distinct from Anaxo of Troezen in the Theseus abduction notice on the Wikipedia Anaxo disambiguation.