Maa Sati or Adishakti incarnated as Goddess Parvati, she was born in the house of sage Katya, hence she was named Katyayani.
Maa Katyayani is the warrior form of Goddess Parvati. Being the most violent form of Goddess Parvati, Maa Katyayani is also the warrior Goddess.
Maa Katyayani is worshipped on the sixth day of Navratri.