Quan Yin is the Chinese Mother Goddess. She also has been called the female Buddha.
In Theosophy and current New Age beliefs, she is considered an Ascended Master, connected to the Temple of Grace & Mercy, in Bejing, China.
As often is the case in these matters, sources contradict each other with regard to alleged incarnations.
Many authors mention incarnations as Isis (Egypt), and Ishtar (Semites) / Inanna (Sumeria).
Some see her as Athena, while others think she was Aphrodite.
(For what it's worth, Sitchin usually equates Ishtar with Aphrodite, not Athena).