Catherine of Austria (Polish: Katarzyna Habsburżanka; Lithuanian: Kotryna Habsburgaitė; 15 September 1533 – 28 February 1572) was one of the fifteen children of Ferdinand I, Holy Roman Emperor and Anna of Bohemia and Hungary.

The dynasty would continue, strictly speaking, for one more reign—that of Sigismund Augustus’ sister, Anna Jagiellon, who was crowned with the male title of Rex Poloniae.

She spent most of her childhood at Hofburg, Innsbruck and received education based on discipline and religion, learning the Italian and Latin languages.

[1] On 17 March 1543, Catherine was betrothed to Francesco III Gonzaga, Duke of Mantua and Marquess of Montferrat, reflecting her father's desire to strengthen Habsburg influence against France in northern Italy, particularly Milan.

In October 1549, Catherine with a dowry of 100,000 Rhine florins was escorted by her elder brother Ferdinand II, Archduke of Austria from Innsbruck to Mantua.

[2] The marriage lasted only four months as Francesco drowned in Lake Como on 21 February 1550, and a widowed Catherine returned home to Innsbruck.

[2] Radziwiłł had further orders to travel to investigate marriage opportunities with Mechthild of Bavaria or one of the daughters of Ercole II d'Este, Duke of Ferrara.

[6] At the end of April, the royal couple traveled to Lithuania and on 25 May reached Vilnius where with short breaks Catherine lived for nine years.

It seems that Catherine accompanied her husband to general sejm in spring 1555 and to the per procura wedding of Sophia Jagiellon and Henry V, Duke of Brunswick-Lüneburg in January 1556.

[7] She also continued to mediate between her husband and her father, carried frequent correspondence with Albert, Duke of Prussia, and was known for generally favorable views on Protestantism.

Catherine's dowry was paid by her father at the end of 1555 or very early 1556, and on 19 January 1556, she received the towns of Wiślica, Żarnów, Radom, Nowy Korczyn, Kozienice, Chęciny, and Radoszyce.

The new emperor sent his diplomats Andreas Dudith and Wilhelm von Kurzbach to try to reconcile the couple, or if that failed, to convince Sigismund to allow her to leave Poland.

Initially Sigismund refused, fearing that it would only increase the anti-Polish sentiment in the Habsburg court, but later changed his mind because he believed that Catherine's departure would make it easier to obtain a divorce.

[10] Emperor Maximilian II extended her stay and wanted to meet with Sigismund personally to discuss the issue, but he refused.

[12] She was visited by her family, she studied the Bible and other theological works, and established a garden for medicinal herbs which produced various herbal remedies.

When Rudolf II, Holy Roman Emperor, ordered reconstruction of the castle, her body was moved to the St. Florian Monastery on 22 September 1599.