Ulrika Eleonora or Ulrica Eleanor (23 January 1688 – 24 November 1741), also known as Ulrika Eleonora the Younger, was Queen of Sweden from 5 December 1718 until her abdication on 29 February 1720 in favour of Frederick, her husband. Upon his accession, as King Frederick I, she served as his queen consort until her death on 24 November 1741.
Ulrika Eleonora was the youngest child of Sweden's King Charles XI and his wife, Ulrika Eleonora of Denmark. She was named after her mother, who became known as Ulrika Eleonora the Elder. In 1715, the younger Ulrika married Frederick of Hesse-Kassel. After the death of her brother Charles XII in 1718, she claimed the Swedish throne. By primogeniture, Charles Frederick of Holstein-Gottorp, son of Hedvig Sophia, her deceased elder sister, had the better claim; but citing the precedent of Queen Christina, Ulrika Eleonora asserted that, by proximity of blood, she was the closest surviving relative of the late king. After agreeing to renounce the powers of absolute monarchy established by her father, she was recognized as successor by the Riksdag. She abdicated on 29 February 1720.
Princess and regent
thumb|150px|left|Ulrica Eleonora's parents, King Charles XI and Queen Ulrica Eleonora the Elder
After their mother's death in 1693, Ulrika Eleonora and her siblings were placed in the care of their grandmother, Hedwig Eleonora. However, her grandmother was known to favor her elder sister. During her childhood, Eleonora was somewhat overlooked in favor of this elder, more extroverted and talented sister, princess Hedvig Sophia. Her elder siblings enjoyed riding and dancing and reportedly somewhat looked down upon her as she did not have the courage to participate in their games and was easily brought to tears. She was described as friendly, modest and dignified, with good posture and beautiful hands, but she was not regarded as either intelligent or attractive. Her grandmother, Hedwig Eleonora, described her as stubborn, and she was known to demonstrate her dislike of others or of events by simulating illness. She was a talented musician, and when performing with her sister at court concerts, she would play the clavier while her sister sang. These plans were about to be put into effect when they were disrupted, without motivation, by her brother. She was later made the god-mother of Louisa Ulrika of Prussia, who was named Ulrika after her.
After her grandmother's death in 1715, she became the center of the court, and this was one of the happiest periods of her life. In 1715, she married Landgrave Frederick I of Hesse-Kassel. The marriage, which on her side was a love-match, became another attempt to use her as a political puppet. Frederick had married her with the intent of reaching the throne, and immediately began plotting to have her named heir in place of her nephew. The "Hesse Party" and the "Holstein Party" stood against each other in the struggle for the throne.
Ulrika Eleonora's situation began to change after the death of her older sister, Hedvig Sophia, in 1708. Ulrika Eleonora became the only adult member of the royal house present in Sweden, aside from her grandmother, Queen Dowager Hedwig Eleonora. Already in late 1712, Charles XII had thoughts of making her regent during his absence. The royal council convinced her to be present at their meetings and give them her support. On 2 November 1713, she appeared at her first session, and a decision was made to assemble the Riksdag to declare her regent in her capacity as the closest heir to the throne. which was considered to be an impressive act of courage. Her favorite courtier was Emerentia von Düben (1669–1743), her old nurse, who had been ennobled and made lady-in-waiting in 1707 and with whom she had a close relationship all her life. Düben acted as her advisor, her comfort and her support, and was said to not have abused her influence – they were described as sisters. During her short reign, to secure support for her rule, she ennobled many families. In a period of fifteen months, she ennobled 181 people, more than any other monarch in Swedish history; one count, two barons and eight lesser noblemen every month. She had seven field marshals where her brother only ever had between three and five. Ulrika Eleonora was in fact in favour of an absolute monarchy. She had agreed to the new constitution only to secure the throne from her nephew, and her relations with the council were not good. She came into conflict with the president of the Privy Council Arvid Horn, who resigned in protest, as well as with his successor Gustaf Cronhielm. Horn criticized her for discussing state affairs with her husband, pressed her as to whether she would respect the constitution and insulted her by making the remark that nothing better was to be expected "under the regiment of a female." These conflicts had a deleterious effect on the war and state affairs.
Ulrika Eleonora supported the political ambitions of her consort, and from the beginning, she wished for him to become her co-monarch, in the fashion of William III and Mary II. However, this was not permitted by the Riksdag. One reason being that co-reigning had been forbidden in Sweden since the 15th century. There was also opposition in the Riksdag to the influence of Emerentia von Düben and her siblings over the affairs of state. Her difficulty in respecting the constitution and trouble in getting along with the Riksdag, as well as her way of continuously discussing state affairs with her husband, did however make the Riksdag willing to replace her with Frederick as sole monarch if she abdicated, an idea that had the support of Frederick. On 29 February 1720, after having again been denied a co-monarchy, Ulrika Eleonora abdicated in favour of her husband on the condition that she should succeed him if he should die before her.
King Frederick suggested placing his brother and his line in the House of Hesse in the succession line, and though this attempt was unsuccessful, Ulrika Eleonora supported this choice rather than her nephew the Duke of Holstein-Gottorp.
Queen Ulrika Eleonora enjoyed great popularity during the reign of her spouse, partly as the last member of the old royal house, and partly because of her personal piety. King Frederick had mistresses, and his extramarital affairs increased after he lost much of his royal authority in 1723.
In 1734, Frederick became the first king in Swedish history to have an official mistress, the noblewoman Hedvig Taube, who was given the title Countess of Hessenstein. Ulrika Eleonora expressed her disapproval to her close confidant Emerentia von Düben, her reason for this was opposition toward the theatre among the clergy.
Queen Ulrika Eleonora died of smallpox in 1741. There were rumours that she had been poisoned, but these rumours were silenced when the marks of her illness were visible during her public lit de parade. As she had been the heir to the throne, her death marked the beginning of a succession crisis.