Jón Rögnvaldsson (died 1625) was an alleged Icelandic sorcerer. The bailiff Magnus Björnsson had been educated in Copenhagen where he read about witch persecutions from an event in 1487. He had brought this book with him to Iceland. In 1625 he heard a rumour that ghosts had made a boy ill and killed several horses. He evidently made the assumption that this had been caused by unknown witches, who needed to be exposed. The sick boy pointed out Jon Rögnvaldsson. During the search of his house an arch of paper with Icelandic runes written on it was found. Jon admitted to having written them. Jon's brother, the poet Thorvald Rögnvaldsson, testified in his defense that although Jon might have attempted to use rune magic, so called Galdrar, he had neither the strength nor the intelligence to suc