Christina (or Christian) Bruce (b. c1273 Seton, East Lothian, Scotland – 1356/1357) the second daughter of Robert de Brus, jure uxoris Earl of Carrick and Marjorie of Carrick, and an older sister of King Robert I of Scotland.
Along with the king's other female relatives, she was captured shortly after his rebellion. However, she avoided the fate of her sister Mary Bruce and Isabella MacDuff (the Countess of Buchan), who were imprisoned in cages, but was sent to a convent in Lincolnshire.
She was married three times. Her husbands were Gartnait, Earl of Mar, (d. 1305) Christopher Seton (d. 1306), and lastly Sir Andrew Murray.
In 1335, during the Second War of Scottish Independence, she commanded the garrison of Kildrummy Castle and successfully held the castle against the forces of the pro-Balliol forces led by David of Strathbogie prior to their defeat by her husband, Sir Andrew Murray, at the Battle of Culblean.
Text taken from http://en.wikipedia.org