Catherine of Brandenburg (Königsberg, 28 May 1604 – 27 August 1649, Schöningen) was princess of Transylvania between 1629 and 1630.
She was the daughter of John Sigismund, Elector of Brandenburg and Anne of Prussia.
On 2 March 1626 she married Gabriel Bethlen, prince of Transylvania, who made her his successor in June 1626.
When the prince Gabriel Bethlen died on 25 November 1629, she tried in vain for a year to hold on to the throne, supporting herself on her favorite Istvan Csaky. Her policy was to bring Transylvania back under the influence of Holy Roman Emperor Ferdinand II, but she was forced to abandon power on 21 September 1630.
The Sublime Porte, first chose her brother-in-law István Bethlen as successor, but finally she was succeeded by George I Rákóczi. The new prince George I Rákóczi was elected on 1 December 1630.
Catherine of Hohenzollern moved back to Germany where she converted to Catholicism in 1633 and married in 1639 Francis Charles of Saxe-Lauenburg. She died on 27 August 1649.