Final answer:
Mary, Queen of Scots, the Catholic mother of Protestant King James VI of Scotland and James I of England, was executed for plotting to overtake the English crown.
Step-by-step explanation:
The term for the 'Called Queen of Scots; Catholic mother of a noted Protestant king' refers to Mary, Queen of Scots. She was the mother of James VI of Scotland, who also became James I of England after the Union of the Crowns. Mary was a devout Catholic who was seen as a threat to Protestant England, leading to her execution after being found guilty of a plot to assassinate Queen Elizabeth I. James I was a Protestant king, known for commissioning the King James Version of the Bible, despite his mother's Catholic faith. This historical figure from the 16th century generated much romanticist interest and is known as the 'Queen of Scots'.