Princess Catherine Ivanovna of Russia (Russian: Княжна Екатери́на Ива́нновна; 12 July 1915 (O.S.) – 13 March 2007) was a great-great-granddaughter of Tsar Nicholas I of Russia and a niece of King Alexander I of Yugoslavia. She was the last member of the Imperial Family to be born before the fall of the dynasty. She was also a second cousin of Prince Philip, Duke of Edinburgh, as Catherine's grandfather Grand Duke Konstantin Konstantinovich of Russia was the younger brother of Prince Philip's grandmother Olga, Queen of Greece. Her relation to Prince Philip makes her a second cousin, once removed of King Charles III of the United Kingdom. She is also the grandmother of actor Sebastian Arcelus.

Born in Pavlovsk Palace, she was the second child of Prince John Konstantinovich of Russia and his wife, Princess Helen of Serbia. After the Russian Revolution, her father was arrested and deported from the capital and her mother followed her husband into exile. Catherine and her brother, Vsevolod, remained in the care of her grandmother, the Grand Duchess Elizaveta Mavriekievna of Russia. On 18 July 1918, their father, Prince John, was killed, and their mother, Princess Helen (Jelena), was arrested and spent several months in Soviet prisons. Grand Duchess Elizabeth was able to take Catherine and her brother to Sweden. Sometime later, they were reunited with their mother. In 1922, On June 8, 1922, as a child, Catherine attended the lavish wedding celebration of her younger uncle, King Alexander I, and Princess Maria of Romania in Belgrade, accompanied by her mother and brother.

At first, the family lived in Yugoslavia, but due to her mother's disagreements with her brother King Alexander I, primarily over the treatment of their brother Prince George (arrested, declared insane, and locked in an asylum in 1925), they eventually left and settled in Côte d'Azur. There, Catherine lived with her mother and brother in the beautiful Villa Trianon (today Villa Aréthuse‑Trianon) in Cap Ferrat, bought for them by their uncle; later became the residence of the King of Laos.

From an early age, the princess showed a keen interest in painting, music, and languages. Her mother made every effort to encourage these talents, taking her on long journeys throughout Italy, where she not only became acquainted with great works of art but also took lessons in drawing and painting. In addition, Catherine attended ballet classes with the renowned dancer and choreographer Ninette de Valois, one of the founders of the Royal Ballet School.

Because of their education, the children later moved to England, where she remained until 1937; her brother attended Eton College and later graduated from the University of Oxford. There, Catherine received an excellent education, attending a school recommended for her and her brother by Queen Mary. She never learned properly the Russian language because her mother, devastated by her husband's death, did not want her children speaking that language in front of her. Neither she nor her brother were encouraged to learn Russian. She acquired, at least, a basic knowledge of the language but never attained fluency, unlike her brother, who never did, despite an effort he made later in life.

From 1937 to 1945, Princess Catherine Ivanovna lived in Italy, with her great-aunt Queen Elena. During her stay she married an Italian diplomat Ruggero Farace, Marchese Farace di Villaforesta (4 August 1909 - 14 September 1970), in Rome on 15 September 1937; on the occasion of her wedding, she renounced her succession rights to the Russian throne. The main obstacle to her marriage was that Princess Catherine did not have an Italian passport, which was especially important in Fascist Italy. At the time, a strict law regulating marriages with foreigners was in force, further complicating the entire situation. Following a series of complications, and with the intervention of her great-aunt, the Queen, and Count Galeazzo Ciano, who was at the time, the Minister of Foreign Affairs, she finally managed to obtain one to proceed with the wedding. Apart from her mother, brother and the Italian royal family, their union was also attended by her two cousins, Prince Christopher of Greece and Grand Duke Dmitri of Russia.

Ruggero Farace, Marchese Farace di Villaforesta (1909–1970) was, at the time of their wedding, a diplomat serving as secretary at the Italian Embassy in Cairo and later, in 1963, became Italy’s ambassador to Uruguay. He was the son of Alfredo, Marchese Farace di Villaforesta (1860–1949), Senior judge at the Italian Supreme Court, member of an old Sicilian noble family, and of his wife, Caterina Fachiri (1882–1968), a Greek aristocrat who was a descendant of some of the most prominent Phanariote families of Constantinople, such as Rallis, Vlastos, Mavrocordato and Rodocanachi. This made her also related to the former ruling families of Wallachia & Moldavia. His mother Caterina suffered deafness inherited from the Fachiri family. She lived into her 90s in Rome. His brother, Alessandro Farace di Villaforesta, was also a diplomat and served at the Italian Embassy in Belgrade during the period of the SFRY.

Through mutual descent from the Princes of Mavrocordato Ruggero was distantly related to Queen Natalia of Serbia (1859–1941), Princess Aspasia of Greece and Denmark (1896–1972) and her daughter Queen Alexandra of Yugoslavia (1921–1993), who was married to his wife's first cousin, King Peter II of Yugoslavia (1922–1970).