Robert Crawley: The Earl of Grantham, head of the Crawley house, husband of Countess Crawley, son of the Dowager Countess, and father to Ladies Mary, Edith, and Sybil. Before he married Cora, the Crawley estate was on the verge of financial ruin; her fortune, which immediately became part of the entail when they married, is what saved Downton from having to be sold.
Cora Crawley: Countess of Grantham, Cora is Lord Grantham's American wife. The Countess had a sizable fortune that legally became her husband's when they married. But because they have not produced a male heir, her money will someday go to Matthew Crawley, Robert's third cousin once removed, his closet male heir.