Caroline of Brunswick, or more completely, Caroline Amelia of Brunswick-Wolfenbuttel, was wife to first cousin George IV. In fact, they only married because of an agreement to pay off George's debts.
Sure, Prince George was no prize, being a drunkard of loose morals, but Caroline was supposedly short, rude, fat, and smelly (in one history book it was said she "smelt like a farmyard"). They wed in 1795, after it was decided that George's marriage 10 years ago to Maria Fitzherbert didn't count, because Maria was a Catholic.
It says a lot about what kind of marriage they would have when, on their honeymoon, George invented his friends over to a house they had rented and even brought his mistress along, Lady Jersey. Of the house, Caroline said it "resembled a bad brothel much more than a palace." Despite all that they had a daughter on Jan. 7, 1796 (if you count, it was just nine months after the wedding, Caroline was denied any rights in the raising of little Charlotte. Shortly after the girl's birth, George even wrote up a will where all he left his wife was one shilling. By 1814, after a "delicate investigation" into her private life, attempts by the king to get a divorce and tell tales against her to the newspapers, Carolyn left England and traveled. Somewhere, available on the web, is a wonderful political cartoon caricature from the time of her with her valet and another manservant (tailor, I think), both of whom she was rumor to have been sexually involved with.
Carolyn returned to the Sceptered Isle in 1820, precipitated in part by the death of her daughter in 1818, to fight for the right to be recognized as queen. The Hoi Polloi were with her for this one, even though popular figures, like the Duke of Wellington, were against - the duke once said to some of her supporters, "Well, gentlemen, since you will have it so, Gd save the queen. And may all your wives be like her." There was a bill in the House of Lords against her, debate on which lasted for months and included the whole Italian servant dalliance while in Europe issue.
Long story short: bill does not get passed, George IV does not get divorced, and Caroline doesn't get to be queen either.
She died shortly thereafter, most likely of intestinal blockage, on August 8, 1821 at the age of 53.