Wikipedia
Katyayini is the sixth form amongst the Navadurga or the nine forms of Hindu goddess Parvati or ( Shakti), worshipped during the Navratri celebrations. this is the second name given for Parvati in amarakosha, the Sanskrit lexicon. (uma katyayani gaouri kali haimavathi iiswari) In Shaktism she is associated with the fierce forms of Shakti or Durga, a Warrior goddess, which also includes Bhadrakali and Chandika, and traditionally she is associated with the colour red, as with Goddess Durga, the primordial form of Shakti, a fact also mentioned in Patanjali's Mahabhashya on Pāṇini, written in 2nd century BCE.
She is first mentioned in the Taittiriya Aranyaka part of the Krishna Yajurveda. Skanda Purana mentions her being created out of the spontaneous anger of Gods, which eventually led to slaying the demon, Mahishasura, mounted of the lion given to her by Goddess Gauri. This occasion is celebrated during the annual Durga Puja festival in most parts of India.
Her exploits are described in the Devi-Bhagavata Purana and Devi Mahatmyam, part of the Markandeya Purana attributed to sage Markandeya Rishi, who wrote it in Sanskrit ca. 400-500 CE. Over a period of time, her presence was also felt in Buddhist and Jain texts and several Tantric text, especially the Kalika Purana (10th century), which mentions Uddiyana or Odradesa ( Odisha), as the seat of Goddess Katyayani and Lord Jagannath .
In Hindu traditions like Yoga and the Tantra, she is ascribed to the sixth Ajna Chakra or the 'Third eye chakra', and her blessings are invoked by concentrating on this point.