Mechtilde of Hackeborn, OSB, also known as Mechtilde of Helfta (born Matilda von Hackeborn-Wippra; 1240/1241 – 19 November 1298), was a Saxon Benedictine nun known for her musical talents and spiritual revelations. At the age of 50, Mechtilde went through a grave spiritual crisis, as well as physical suffering. In the modern Benedictine calendar, her feast is celebrated on the anniversary of her death, November 19. She died in the convent of Helfta, near Eisleben.

Born Matilda von Hackeborn-Wippra, in 1240 or 1241, she belonged to one of the noblest and most powerful Thuringian families; her sister was the illustrious Abbess Gertrude of Hackeborn. The family of Hackeborn belonged to a dynasty of Barons in Thuringia who were related to the Hohenstaufen family and had possessions in northern Thuringia and in the Harz Mountains. Some writers have considered that Mechtilde von Hackeborn and Mechtilde von Wippra were two distinct persons, but, as the Barons of Hackeborn were also Lords of Wippra, it was customary for members of that family to take their name indifferently from either, or both of these estates.

Mechtilde was considered so fragile at birth that the attendants, fearing she might die unbaptized, hurried her off to a priest who was preparing to say Mass. He was thought to be a person of "great sanctity," and, after baptizing the child, is reported to have said "What do you fear? This child most certainly will not die, but she will become a saintly religious in whom God will work many wonders, and she will end her days in a good old age."

When Mechtilde was seven years old, she was taken by her mother on a visit to her elder sister Gertrude, who at that time was a nun in the Cistercian monastery in Rodersdorf. Mechtilde became so enamoured of the cloister that her parents yielded to her requests and allowed her to enter the novitiate. Here, being highly gifted in mind as well as in body, she made remarkable progress in virtue and learning.

Ten years later (1258), she followed her sister, who was now abbess and had transferred the monastery to an estate at Helfta, which had been given to her by her brothers Louis and Albert. As a nun, Mechtilde was soon recognized for her humility, her fervour, and the amiability which had characterized her from childhood. She joined the convent and eventually became the headmistress of the convent school. Mechtilde's duties in the convent included looking after the library, illuminating manuscripts, and writing her own texts in Latin. Mechtilde composed many prayers. In 1261, the abbess committed to her care a five year-old child, who in later generations became known as Gertrude the Great.

Mechthild was famous for her musical talents and beautiful voice, earning her the title of the "Nightingale of Helfta"; she reported that Christ called her his "nightingale" in her visions. She held the office of domina cantrix until her death, presiding over the sacred music in her convent and training the choir.

She was said to never tire of praising God, even when experiencing severe physical suffering. Both troubled people and learned Dominicans consulted her for spiritual advice.

The Lord would say to Mechtilde: "Everything you have and by which you can please Me you have from Me and through Me." In one extraordinary vision, she perceived that "the smallest details of creation are reflected in the Holy Trinity by means of the Humanity of Christ, because it is from the same earth that produced Them that Christ drew His Humanity."