Grand Duchess Alexandra Iosifovna of Russia (born Princess Alexandra of Saxe-Altenburg; 8 July 1830 – 6 July 1911) was the fifth daughter of Joseph, Duke of Saxe-Altenburg and Duchess Amelia of Württemberg.

Alexandra's parents were married on 24 April 1817, at Kirchheim unter Teck. Alexandra had five sisters: Marie, Pauline, Therese, Elisabeth, and Luise.

Alexandra's portrait was painted by the fashionable court artist Joseph Karl Stieler. She was called "Sanny" by her friends and family.

In the summer of 1846, she met her second cousin, Grand Duke Konstantin Nikolayevich of Russia when he visited Altenburg. He was the second son of Nicholas I, Emperor of Russia, and Empress Alexandra Feodorovna, née Princess Charlotte of Prussia.

Konstantin stayed for a few days at Alexandra's father's castle. His visit there had been arranged by Alexandra's aunt, Grand Duchess Elena Pavlovna, who had been born Princess Charlotte of Württemberg. Elena and Alexandra's mother were both descended from Frederick II Eugene, Duke of Württemberg. Elena was married to Grand Duke Michael Pavlovich, the younger brother of Tsar Nicholas I. Elena Pavlovna was therefore Konstantin's aunt by marriage and Alexandra's aunt by birth. Elena was a strong influence over Konstantin, who admired her intellect and progressive views. She had literary interests and was musical, founding the St Petersburg Conservatoire, and the young Konstantin often spent time at Elena's home and salon in St Petersburg.

Konstantin was intellectual and liberal, whereas Alexandra was conservative and rather high spirited. Although their temperaments differed, they both shared an interest in music, and enjoyed playing duets at the piano. Konstantin was captivated by Alexandra's youthful beauty: she being tall, slender and attractive. He quickly became besotted, and was eager to marry her "I don't know what is happening to me. It is as if I am a completely new person. Just one thought moves me, just one image fills my eyes: forever and only she, my angel, my universe. I really do think I’m in love. However, what can it mean? I've only know her just a few hours and I'm already up to my ears in Passion". She was only 16 and Konstantin 19; they were engaged but had to wait two more years before they could finally marry.

Alexandra arrived in Russia on 12 October 1847, and was greeted by much fanfare and popular celebration, with jubilant crowds lining the streets and balconies. It was said that Alexandra looked so much like her fiancé's sister, the Grand Duchess Alexandra Nikolayevna, who died in childbirth, that her prospective mother-in-law burst into tears at their first meeting.

In February 1848, Alexandra converted to Russian Orthodoxy, taking the name of Grand Duchess Alexandra Iosifovna, which reflected her father's name Joseph (unlike many princesses she took a patronymic, choosing to reflect her parentage rather than the usual religious or dynastic associations which was also possible because Iosif was a common name in Russia).