Vajrayogini - An Introduction
Naropa's VajrayoginiVajrayogini or Vajravarahi as a tantric Buddhist meditational deity (Tibetan: yidam or Sanskrit: ishtadeva) comes to us in many forms and from various lineages. She embodies principally: (1) the fully enlightened female, wild, fiery, and energetic (shakti/kundalini) aspect of a Buddha; (2) the wisdom (= experiential) aspect leading to Buddhahood; and (3) as a principal dakini (Tibetan: mKha' gro; "sky-goer") the (com)passionate guiding and inspirational aspect leading the practitioner to enlightenment.

Vajradakinis
In Anuttara Yoga Tantra the principal dakini (often called "Vajra-" or "Wisdom-dakini") is mostly shown in union with a male consort, like in the deities Guhyasamaja, Hevajra, Kalachakra, etc. In our case, Vajrayogini/Vajravarahi is the principal female buddha in the Chakrasamvara Tantra and is in union with Heruka Chakrasamvara. Since the Vajradakinis are considered buddhas and yidams in their own right over time several spin-off practices have evolved from those practices simplifying the otherwise complicated main practice and reducing it to a single-deity meditation without dropping the principal aspects/benefits of the main practice (e.g. Vajrayogini/Vajravarahi out of Chakrasamvara and Nairatmya out of Hevajra).