She was born in Scotland on 8 December 1542 and became Queen only six days later when her father James died. Her coronation was nearly a year later. It was planned that she should marry a French prince, Francis, when she grew up and she was sent to live in France with her mother's family when she was five years old.
Mary married Francis in 1558 but his health was bad and he died soon after, so she moved back to live in Scotland.
In 1565 Mary married a man called Henry Darnley, but things didn't work out and he started behaving quite badly to her. This didn't stop them having a baby together, and in 1566 their son James was born. Darnley was behaving so badly that he was suspected of helping to murder Mary's friend Riccio.
Darnley died that year in a huge explosion, which Mary's next husband Lord Bothwell might have been involved in. She married Bothwell in 1567 although lots of people thought this was wrong.
Later that year, Mary was imprisoned in Lochleven Castle by Scots people who didn't want a Catholic queen. She managed a dramatic escape the next year, and decided to go to England to look for help from her cousin Queen Elizabeth.
Elizabeth wouldn't help her, however, and instead kept Mary locked up as a prisoner. This was because many people in England felt that Mary had a better claim to the English throne than Elizabeth did. Several years later (in 1586) Elizabeth had Mary sentenced to death for treason (trying to overthrow the King or Queen). Mary was executed by beheading a year later.