1. Mary was a 1st century Galilean Jewish woman of Nazareth, the wife of Joseph and the mother of Jesus, according to the canonical gospels and the Quran. According to Christian theology, Mary conceived Jesus through the Holy Spirit while still a virgin, and accompanied Joseph to Bethlehem, where Jesus was born. (Wikipedia).
She is revered as Mother Mary in most Christian religions, and especially in Catholicism.
Not much is known about her. The Dead Sea Scrolls confirmed what Edgar Cayce had said before, i.e., that she belonged to the sect of the Essenes.
2. As Lady Mary, she is also considered one of the main Ascended Masters.
According to Edmund Harold, "The vibration of Lady Mary corresponds to that of the Moon, which in turn relates to the Feminine Principle of the Supreme Source of All Life - God. (...) She will seek to encourage adaptability and cooperation within all walks of life, for all under her tutelage must learn to blend with their environment, becoming powerful through the virtue of their cooperation. (...)
Within the age yet to come, it is in the field of sensitivity that the influence of this Illumined One will be most potent. She has inspired humanity throughout the ages, firstly as the moon goddess Ishtar, where she brought her influence to bear upon the Mesopotamian culture, later in Greece where she was revered as the goddess Diana, and in modern times, as the Virgin Mother of the Master Jesus. The manifestation of the energies of this illumined one have, therefore, long provided a signal for humanity to begin once more the expansion of the feminine, or intuitive, aspects of the nature. In particular, those who are born upon the number 2 vibration must make strong endeavors to develop their inner qualities, taking care to utilize these for the overall benefit of humanity."
Source: Edmund Harold, Master Your Vibration, p. 31.