| Olga Cantacuzène-Altieri | |
| Princess Cantacuzène-Altieri | |
| Birth Date: | 25 November 1843 |
| Birth Place: | Odessa, Kherson Governorate, Russian Empire |
| Death Date: | 25 November 1929 (aged 86) |
| Death Place: | Gattaiola, Province of Lucca, Tuscany, Kingdom of Italy |
| Noble Family: | Cantacuzino family (by birth) Altieri family (by marriage) |
| Father: | Prince Alexander Nikolaevich Cantacuzène |
| Mother: | Maria Ivanovna, née Baroness Renault |
Princess Olga Cantacuzène-Altieri (; 1843–1929) was a Russian-Italian aristocrat and novelist who wrote in French.
Princess Olga Alexandrovna Cantacuzène, the daughter of Prince Alexander Nikolaevich Cantacuzène, a retired captain, was born on 25 November 1843 in Odessa. Her mother, Princess Maria or Marie Ivanovna, née Baroness Renault, was the daughter of an honorary citizen of Odessa. Olga's paternal grandfather, Major-general Prince Nikolai Rodionovich Cantacuzène, died two years before the birth of his granddaughter. The family lived in Odessa, in the house of the Cantacuzènes.
In 1857, when Olga was fourteen years old, her father died and a year later her mother went to travel around Europe. In Paris, she became close friends with the mistress of the fashion salon, Princess Mathilde Bonaparte, daughter of Napoleon's younger brother, Jérôme. There, in 1862, she met Count Nieuwerkerke, who fell in love with Olga. In 1872, the Count bought a 16th-century villa in Italy, where he settled himself, and invited the entire Cantacuzène family there.
Count Nieuwerkerke found a worthy groom for Olga, and in 1876 she married a representative of an ancient Italian family, Prince Lorenzo Maria Guiseppe Altieri-Oriolo (1829–1899). In the late 1870s and early 1880s, Olga and her husband travelled widely in Europe, Asia, Australia, and America. Olga began to record her impressions of what she saw in her diary. It turned out that she had literary abilities. One after another, books began to appear. Many of them have been republished, but nothing has been translated into Russian to this day.
She died in Gattaiola, Italy, on 25 November 1929.