Noël Leslie, Countess of Rothes

Though she's barely in the movie, the Countess of Rothes, played by Rochelle Rose, was actually a heroine of the Titanic disaster. She helped steer her lifeboat away from the sinking ship and then to the rescue ship. She was also mentioned in Downton Abbey as being someone that the Crawleys had seen shortly before the sinking. (Remember? Matthew only inherited because some other Crawley relative died on the Titanic.)