Märet Jonsdotter (1644 – September 1672) was an alleged Swedish witch. She is one of the most known victims of the persecutions of sorcery in her country; she was the first person accused of this in the great witch hysteria called "Det Stora Oväsendet" ("The Great Noise") of 1668–1676, and her trial unleashed the beginning of the real witch hunt in Sweden, which was to cause the death of around 280 people in those eight years. She was known by the name "Big Märet" because she had a younger sister with the same name called "Small Märet" Jonsdotter.
In the autumn of 1667, a little shepherd boy in Älvdalen in Dalarna, Mats Nilsson, claimed to have seen a girl lead goats over Eastern Dalälven by walking on the water at Hemmansäng by Åsen. This little boy had tended the herd of sheep with this same girl, they had had a fight, and the girl had beaten the boy up. The girl's name was Gertrud Svensdotter (Svensdotter meaning "daughter of Sven"). She was twelve years old.
Gertrud Svendsdotter was then interrogated by the priest, Lars Elvius, who encouraged her to say that she had indeed walked on water, and that she had done so by magic, which had been given to her by the Devil. After long talks with the vicar, Gertrud said that while she lived with her parents in Lillhärdal in Härjedalen, a neighbour's maid had taken her to the Devil. The name of the maid was Märet Jonsdotter.
Gertrud Svendsdotter made a detailed confession to the priest. She claimed that, in 1663, when she was eight, Märet had taken her on a walk. They had passed a sand-pit, and then came to a three-way crossroads, where Märet had cried out: "Thou Devil, come forward!". She claimed that Satan had then appeared in the shape of a vicar. They had dined, and the following night, Märet had come to Gertrud and smeared her body and one of her father's cows with a red oil, after which they had flown away through the chimney and all the way to Satan.
Since then, Gertrud had often visited Blockula, milked cattle with familiars, smeared her feet with oil to walk on water and taken children to Blockula, where their names had been written in a book with black pages. The reason she had admitted this was that she had met an angel in Blockula, a man in white, who had told her to confess, or else a hunger epidemic would sweep over the kingdom.