Princess Yekaterina Mikhailovna Dolgorukova (Russian: Екатери́на Миха́йловна Долгору́кова; 14 November 1847 – 15 February 1922), also known as Catherine Dolgorukova, Dolgoruki, or Dolgorukaya, was the daughter of Prince Michael Dolgorukov and Vera Vishnevskaya. She was a long-time mistress of Tsar Alexander II of Russia and later, as his morganatic wife, was given the title of Princess Yurievskaya (Светлейшая княгиня Юрьевская).

Alexander and Catherine already had three children when they formed a morganatic marriage on 18 July [O.S. 6 July] 1880, after the death of the Emperor's wife, Marie of Hesse and by Rhine, on 3 June [O.S. 22 may] 1880. A fourth child had died in infancy. Catherine became a widow with the assassination of Alexander II on 13 March [O.S. 1 March] 1881 by members of Narodnaya Volya.

Catherine first met Alexander when she was twelve and he paid a visit to her father's estate. At the time, he saw her only as a little girl and probably forgot their visit. After the death of her father, who had left his family without resources, Catherine and her sister were sent to the Smolny Institute for Noble Maidens in St. Petersburg, a school for well-born girls. The Tsar paid for their education and that of their four brothers. Alexander met the sixteen-year-old Catherine there on an official visit to the school in the fall of 1864 and was immediately attracted. One contemporary described the young Catherine as "of medium height, with an elegant figure, silky ivory skin, the eyes of a frightened gazelle, a sensuous mouth, and light chestnut tresses." He visited her at the school and took her for walks and on carriage rides. Catherine had liberal opinions, formed in part by her time at the school, and she discussed them with the Tsar. He later arranged for her to become a lady-in-waiting to his wife, who was suffering from tuberculosis.

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