Catherine Stenbock (Swedish: Katarina Gustavsdotter Stenbock; 22 July 1535 – 13 December 1621) was Queen of Sweden from 1552 to 1560 as the third and last wife of King Gustav I.

Early life Catherine Stenbock was born on 22 July 1535 in Torpa Castle, Sweden. She was the daughter of Riksråd Gustaf Olofsson Stenbock and Brita Eriksdotter Leijonhufvud, who was the sister of King Gustav's previous consort Margaret Leijonhufvud. She was thus the maternal niece of Queen Margaret and first cousin of the royal children of that marriage, including future kings John III of Sweden and Charles IX of Sweden. Her siblings included Ebba Stenbock.

There is little information about her prior to her marriage. It is possible that she served as maid of honor to her aunt, the Queen, but either way, she was most certainly known to the King personally: due to the marriage of her aunt, her family belonged to the relations to the King named as Kungafränderna (`The King's Relations´), who played an important role at court, and participated in the family events of the monarch, as well as he was present at the weddings and other events of her family.Tegenborg Falkdalen, Karin, Vasadrottningen: en biografi över Katarina Stenbock 1535-1621 [The Vasa Queen: A biography of Catherine Stenbock, 1535-1621], Historiska media, Lund, 2015 Her parents were both favored by the monarch. Their marriage was hosted by the King in parallel to his own first marriage in 1531, her father founded his career as a riksråd upon his loyalty to the King, and her mother was in the King's confidence: it was said that "In her [Queen Margaret's] sister Bridget... he always had much trust". Upon the death of her aunt Queen Margaret in 1551, Catherine's mother Brita and aunt Martha Leijonhufvud, in succession to Christina Gyllenstierna, were entrusted the care of the royal children until the King married again, which he was expected to do.

The King declared that a new marriage was necessary foremost because he needed a Queen for his court and a mother for his young children. In March 1552, he called her mother, her aunt Martha and her spouse, and the King's nephew Per Brahe the Elder who was married to Catherine's sister Beata, and it thought that her proposed the marriage to her family at this meeting. Her family was favorable to the match, as this would preserve the family connection they had made with the King through his previous marriage with Queen Margaret, an influence they would keep through Catherine. The reason the King stated to marry Catherine was the great costs and the time-consuming negotiations necessary secure a marriage with a foreign princess in the complicated political climate in Europe during the ongoing religious conflicts. The marriage to Queen Margaret had secured the King a loyal support with the Swedish nobility for his rule, a useful alliance with he confirmed by marrying again in to the same family by marrying the niece of his late spouse. Catherine herself is described as a 155 cm tall, dark blonde beauty with blue eyes.

According to tradition, like her aunt and predecessor Catherine was engaged when the King decided to marry her, to the noble Gustav Johansson Tre Rosor (His last name meaning Three Roses), and after the marriage to the King, he once heard her say in her sleep: "King Gustav is very dear to me, but I shall never forget The Rose". When the King came to her parents manor Torpa to propose to her personally, as the law demanded that she give her personal consent, it is said that she ran away and hid behind a bush in the garden. Whether truthful or not, the King had his way.

There was, however, opposition among the church against a marriage between the King and the niece of his former spouse, and the arch bishop protested quoting the Books of Moses prohibiting the marriage between a man and the widow of his uncle, which was interpreted as the ban against marriage to the relations of a dead spouse. The King had a commission headed by Georg Norman prove that the Old Testament applied only to Jews and that, in any case, it allowed for a man to marry the sister of his dead wife and thereby a marriage to the niece of his wife must be permitted. The King also had his royal council confirm to the church that the King married upon their request out of the need for a Queen rather than for an infatuation and that he had the right to marry whom he choose, after which the church agreed to the marriage.

Queen The marriage was conducted in the chapel of the Vadstena Abbey 22 August 1552, followed by the coronation of Catherine as Queen the following day. She was dressed in a golden dress during the wedding, and a silver one during her coronation, escorted, as was Queen Margaret during official ceremonies, by her male relatives. The wedding was surrounded what was seen as bad omens: the plague swept through parts of the nation, the city of Turku burned down, and people claimed to see bad omens and evil signs in the sky. The celebrations lasted for three days. When the court departed, the city of Vadstena burned down in a great fire, which was seen as another bad omen.

There is little information of Catherine Stenbock as Queen. As such, she was, with the assistance of her head lady-in-waiting Anna Hogenskild, made responsible to supervise the female courtiers and her cousins, the royal children; in the case of the princesses, until they married, and in the case of the princes, until they were no longer children. It seems as if her relationship to her royal stepchildren was a good one, with the exception of Duke Charles. Her private relationship to the King is not much mentioned, and it has been said that she: "Accepted her part as Queen of Sweden with silent dignity" and without attracting too much personal attention. It is said, however, that the King did find their age difference too great and contemplated writing a law which would prevent any future marriage between: "Two people, of which one was young and one was old". As Queen, she was expected by her family to replace her aunt Queen Margaret in the role of acting as a loyal as a channel between her family and the King, preserving the influence of her family, a task she obediently fulfilled: in 1556, for example, she was asked by her aunt Martha Leijonhufvud of a document from the King regarding the rights to Läckö fief, a task she performed successfully. There are no information that she ever involved herself in any personal political agenda of any kind. One of the few incidents mentioned of her during her tenure as Queen was during the conflict between the young courtier Hogenskild Bielke and her brothers Erik and Olof, in which Bielke accused Olof and Erik of using their positions as brothers of the Queen to terrorize the other young male courtiers while being protected by Catherine. Her stepson John's lover Karin Hansdotter originally belonged to her court.

In 1554 and in 1556, there were signs that she was pregnant, but no pregnancy was ever officially announced and none was ever confirmed.Suomen kansallisbiografia 5, sivu 58 In 1555, she and the royal children accompanied the King to the province of Finland, where they stayed until 1556. During their stay on Åland, where they spend the winter upon their return after their visit to Finland, Catherine was affected by "Sudden motherly problems", which has been interpreted as a miscarriage, which is the closest information available of a pregnancy of Catherine Stenbock.

In Stockholm on 1 October 1559, she was present at the wedding between her stepdaughter Princess Catherine and Edzard II, Count of East Frisia. On their departure from Sweden, the newly weds was accompanied by the sister of the bride and the brother of the groom, Princess Cecilia of Sweden and Johan II of East Frisia. On their stay in Vadstena, Cecilia and Johan were discovered by Crown Prince Eric to have a sexual affair. The great scandal were to be known as Vadstenabullret (Vadstena Rumble). Catherine and Edzard were placed in house arrest, Johan were imprisoned, while Eric and Cecilia where both called back to Stockholm. The King is said to have cried when he related the story to Queen Catherine. During the whole affair, Catherine Stenbock was on numerous occasions asked to act as mediator between the King and his children. She accompanied Cecilia to her confrontation with her father after her return to the capital, and she acted as channel through the King for Princess Catherine, who tried to negotiate Johan's release and permission for her and her spouse to leave for East Frisia. In May 1560, Prince Eric asked her for a permission from his father to travel to England to propose to Elizabeth I of England.

King Gustav fell sick and died during the scandal. According to the chronicles, Catherine was present by his bedside during his entire sickness until death, had a bed brought in by his side where she slept, and eventually fell sick herself. She continued to act as mediator between the King and his children, and upon his complaints that they were not there, answer that they would have been, and wished to, had they not been so afraid for his anger.

Reign of Eric XIV King Gustav died on 29 September 1560 and was succeeded by his son in his first marriage, Eric XIV. In his will, Catherine was promised custody of the Princesses, who were to live at the court of Eric or her until they married, an allowance suitable for her position, and that his sons should always see to it that she had her needs taken care of. He did not specify which estates should be given to her in his will, but prior to his death, he had his two eldest sons Eric and John promise to grant her preferred choice, Strömsholm. In March, Catherine had Eric XIV issue a written statement of her right to Strömsholm, which remained her seat for the rest of her life, as well as several other lands and parishes in Södermanland, as well as her own residence in the capital. The mother of the new King's infamous adviser Jöran Persson, Anna, was the house keeper of the Queen Dowager's court at Strömsholm.

Catherine Stenbock remained a widow for 61 years, and despite participating in various kinds of ceremonies, she dressed in mourning for the rest of her life. She was the first Swedish Queen Dowager referred to by the title Riksänkedrottning (Queen Dowager of the Realm). During most of the reign of Eric XIV, the King was unmarried, and Queen Dowager Catherine ceremoniously functioned as the first lady of the royal court. In 1562, for example, she and the King opened a ball given in honor of the Polish embassy sent to negotiate the wedding between the King's brother Prince John and the Polish Princess Catherine Jagellon.

Queen Dowager Catherine seems to have had a good relationship to Eric XIV, who normally treated her with respect, referred to her as "My Dear Stepmother" and trusted her on certain critical occasions. During the conflict between the King and his brother Prince John, when the King had John imprisoned with his spouse, Catherine offered her assistance as mediator, but was refused by Eric who accused her of siding with John and reminded her that King Gustav had asked them all to show loyalty to his successor.