Gargi Vachaknavi
Gargi (गार्गी) or Vachaknavi (वाचक्नवी) was a female sage and philosopher.
In the sixth and the eighth chapters of Brihadaranyaka Upanishad, her name is prominent as she participates in the philosophic debate organized by King Janaka of Videha. she challenged the sage Yajnavalkya with her questions related to Atman (soul).
Gargi, got another name as Vachaknavi (वाचक्नवी), the daughter of sage Vachaknu (वचक्नु)
Adi Shankaracharya mentioned in the commentary of Brihadaranyaka Upanishad 3.6.1 –
“वाचक्नवी वचक्नोर्दुहिता” means “Vachaknavi was the daughter of rishi Vachaknu”
Vachaknavi (वाचक्नवी) in Upanishads
अथ हैनं गार्गी वाचक्नवी पप्रच्छ – Brihadaranyaka Upanishad 3.6.1
अथ ह वाचक्नव्युवाच ब्राह्मणा भगवन्तो हन्ताहमिमं द्वौ प्रश्नौ प्रक्ष्यामि – Brihadaranyaka Upanishad 3.8.1