Elisabeth Christine Ulrike of Brunswick-Wolfenbüttel (Elisabeth Christine Ulrike; 8 November 1746 – 18 February 1840), was a Crown Princess of Prussia as the first wife of Crown Prince Frederick William, her cousin and the future king Frederick William II of Prussia.
She was the seventh child and third daughter of Charles I, Duke of Brunswick-Lüneburg and Princess Philippine Charlotte of Prussia, the sister of Frederick the Great. She held the rank of Duchess in Brunswick with the style and title Her Serene Highness Princess Elisabeth Christine.
As the maternal niece of the king of Prussia and the paternal niece of the queen of Prussia, she was selected to marry her cousin Crown Prince Frederick William, by his uncle, the childless King, with the purpose of producing heirs to the Prussian throne.
The marriage ceremony between Elisabeth Christine and Crown Prince Frederick William was originally planned to take place at Charlottenburg Palace's Chapel, but in the end took place on 14 July 1765, on the family country estate Schloss Salzdahlum.
Elisabeth Christine was described as handsome to her appearance, engaging and graceful in manner, lively, high-spirited and impetuous in disposition, and was admired for the grace of her dancing. Her beauty, intelligence and spirited manner made her a favorite of her uncle the king, otherwise very seldom interested in women, who considered her to be witty and had very little sympathy for the adultery of her spouse.
Soon it became clear the couple was not happy with each other. King Frederick had hoped that the marriage would lead to the production of an heir, but instead noticed that Frederick William neglected his wife and was unfaithful to her on a daily basis with a series of dancers and actresses. When their first child proved to be a girl, Princess Frederica Charlotte, their relationship deteriorated.
This was described in Vertraute Briefe as: "Frederic William was now twenty-one years of age; his disposition was good, but his capacity was slender; he resembled the Bruns wicks in person, being six feet two in height, and proportionally stout. But he was unfortunately addicted to the grossest sensuality, and his time, when not occupied by his military duties, was spent with vile women and other loose companions. His young wife resented this conduct in the highest degree; wounded alike in her wifehood and her womanhood, she not only separated herself from the crown Prince, and haughtily refused him admission to her presence, but, alas! She sacrificed even virtue to revenge."
Wounded by her husband's neglect and infidelity, the Crown Princess began to have affairs with young officers of the Potsdam Guard. In a letter wrote to his sister (and Elisabeth Christine's mother) Philippine Charlotte, the concerned King says:
This scandal finally erupted when, as was noted by Friedrich Wilhelm von Thulemeyer, the Crown Princess became pregnant by her lover, a musician called Pietro. By late January 1769 they planned to escape to Italy, but she was betrayed. On a masked ball given by Prince Henry in celebration of the king's birthday on 24 January 1769, the crown prince was informed of her affairs by an anonymous person hidden behind a mask, which enraged him despite his own adultery, and made him demand a divorce.
King Frederick was initially unwilling to agree to a divorce, as his sympathy was greater for Elisabeth Christine than for Frederick William, but the crown prince insisted in his demand for a divorce, and urged in agreement with the King the annulment of his marriage on grounds to avoid claims of illegitimate offspring on the Prussian throne, to which the Brunswick court agreed. The musician Pietro was arrested and taken to Magdeburg, where he was reportedly beheaded. Elisabeth Christine terminated her pregnancy with drugs. Her brother, Prince William of Brunswick, was aware of her affairs, and his attempts to hide them and defend her exposed him to suspicions that he himself had been involved in them.
The divorce was officially pronounced on 18 April 1769. Frederick the Great forced his nephew to remarry only three months after the separation.
Elisabeth Christine was firstly banished to Küstrin Fortress and later placed under house arrest as a Prisoner of state in the Ducal Castle of Stettin under the care of her cousin, Duke Augustus William of Brunswick-Bevern. She lost the title of Royal Highness and was given the title of Serene Highness.
At first, she lived in harsh circumstances. Being of an extrovert nature, she suffered from her isolation: reportedly, she sometimes placed all the chairs in a long row in her apartments, and dance "Anglaises" between them to ease her boredom.  She did at one point attempt to escape, and made an agreement with an officer to help her escape to Venice, but the plan was never put in fruition as her accomplice suddenly disappeared. Eventually, King Frederick improved her living conditions, and in 1774, she was given a summer residence in the medieval cloister in Jasenitz.
After the death of Frederick the Great in 1786, she received a visit from her former spouse, and during his reign, her conditions improved: she was given permission to entertain visitors, and to walk, and ride on horseback in the areas of the town. According to Mirabeau, she was offered her release, but declined, as she had by that time grown used to her lifestyle. An incident is known, when she slapped an officer who insisted upon opening a New Year's gift from her mother: when he sent a complaint to the king, he answered "no man could ever be insulted by a blow from the hand of so fair a lady."
Elisabeth Christine never saw her daughter or siblings again; during her later life, King Frederick William IV was the only one who visited her. When the French army occupied Stettin in 1806, the so-called Elisabeth of Stettin moved to a small country estate outside the city walls, which she called Landhaus Friedrichsgnade ('Villa Frederick's mercy').
Elisabeth Christine died at the age of 93. At her death, all the bells of the city rang. She had a mausoleum built for herself in her beloved park because she didn't want to be buried with her relatives in the Ducal Brunswick Crypt. When the park was handed to private hands, she was reburied in the Chapel of the Ducal Castle of Stettin on the night of 19 July 1849. Other sources, however, indicated that she was later reburied in the cathedral of Kraków.
- Princess Frederica of Prussia (7 May 1767 – 6 August 1820) married Prince Frederick, Duke of York and Albany, but remained childless.