Ekaja?? or Ekaja??,, also known as M?hac?na-t?r?,one of the 21 Taras, is one of the most powerful and fierce goddesses of Indo-Tibetan mythology. According to Tibetan legends she is an acculturation of the Bön goddess of heaven, whose right eye was pierced by the tantric master Padmasambhava so that she could much more effectively help him subjugate Tibetan demons. Ekajati is also known as 'Blue Tara'. She is generally considered one of the three principal protectors of the Nyingma lineage, along with R?hula and Vajras?dhu (Dorje Legpa).
Often she appears as liberator in the mandala of Green Tara. Along with that her ascribed powers are removing the fear of enemies, spreading joy and removing personal hindrances on the path to enlightenment.
Ekajati is the protector of secret mantras and "as the mother of the mothers of all the Buddhas," represents ultimate unity. As such her own mantra is also secret. She is the most important protector of the Vajrayana teachings, especially the inner tantras and termas. As the protector of mantra she supports the practitioner in deciphering symbolic dakini codes and properly determines appropriate times and circumstances for revealing tantric teachings. Because she completely realizes the texts and mantras under her care, she reminds the practitioner of their preciousness and secrecy.

She is of a blue skin tone, with a high, red chignon ("she who has but one chignon" is another one of her titles). She has one head, three breast, two hands and a third eye. However, she can also be depicted with more body parts; up to twelve heads and twenty four arms, with different tantric attributes (sword, kukuri, phurba, blue lotus axe, vajra)

In another form her hair is arranged in the same single bun with a turquoise forehead curl. This and her other features signify her blazing Loyalty to no duality. Ekajati's single eye gazes into unceasing space, a single fang pierces through obstacles, a single breast "nurtures supreme practitioners as her children." She is naked, like awareness itself, except for a garment of white clouds and tiger skin around her waist. The tiger skin is the realized siddha's garb, which signifies fearless enlightenment. She is ornamented with snakes and a garland of human heads.
In some representations, she stands on a single leg. Her body is dark in color, brown or deep blue. She stands on a flaming mandala of triangular shape. She is surrounded by a fearsome retinue of mamo demonesses who do her bidding in support of the secret teachings, and she emanates a retinue of one hundred ferocious iron she wolves from her left hand. For discouraged or lazy practitioners, she is committed to being "an arrow of awareness" to reawaken and refresh them. For defiant or disrespectful practitioners, she is wrathful and threatening, committed to killing their egos and leading them to dharmakaya, or the ultimate realization itself. She holds in her right hand the eviscerated, dripping red heart of those who have betrayed their Vajrayana vows.

In her most common form she holds an axe, drigug (cleaver) or khatvanga (tantric staff) and a skull cup in her hands. In her chignon is a picture of Akshobhya.
Her demeanour expresses determination. With her right foot she steps upon corpses, symbols of the ego. Her vajra laugh bares a split tongue or a forked tongue and a single tooth. She is dressed in a skull necklace and with a tiger and a human skin. She is surrounded by flames representing wisdom.

When Ekajati appears to yogins in hagiographies, she is especially wrathful. She speaks in sharp piercing shrieks, her eye boils, and she gnashes her fang. At times she appears twice human size, brandishing weapons and served by witches drenched in blood.