Marjorie Bruce or Margaret de Bruce (December, 1296 - March 2, 1316) was the only daughter of Robert I of Scotland and his first wife Isabella of Mar.

In 1302, her father was remarried to Elizabeth de Burgh. They were crowned King and Queen of Scots at Scone, Perthshire on March 27, 1306. The crowning occurred during the Wars of Scottish Independence in opposition to Edward I of England.

She was captured along with her step-mother and other women of the House of Bruce by the end of June, 1306. Marjorie was captured and locked in a cage in the centre of the town Lanercost for about a year. Edward I of England died on July 7, 1307. He was succeeded by his son Edward II. Edward II had originally planned for her to be moved to a cage at the Tower of London, however, people became angry at his treatment of the girl and he abandoned the idea of moving her to London.
After that Edward II held her in a nunnery for about 8 years. She was finally set free at about 1314. Either shortly before or shortly after the Battle of Bannockburn (June 23 - June 24, 1314).
Walter Stewart, 6th High Steward of Scotland distinguished himself in the battle and was rewarded with the hand of the adolescent Princess of Scotland. Her dowry included the Barony of Bathgate in West Lothian, Scotland.

Two years later Marjorie went horseriding near Paisley, Renfrewshire while pregnant. Her horse was suddenly frightened and threw her to the ground. She went into premature labour. Her first and only son Robert II of Scotland was delivered by caesarean section.

Her reported last words were "He's a laddie; I ken he's a laddie; he will be King". She survived the birth by a few hours at most. Her son would indeed succeed his childless uncle David II of Scotland in 1371.

Her descendants include the House of Stuart and all their successors at the throne of Great Britain.