Mary, also known as Maria of Anjou (Hungarian: Anjou Mária, Croatian: Marija Anžuvinska, Polish: Maria Andegaweńska; 1371 – 17 May 1395), reigned as Queen of Hungary and Croatia between 1382 and 1385, and from 1386 until her death. She was the daughter of Louis the Great, King of Hungary and Poland, and his wife, Elizabeth of Bosnia. Mary's marriage to Sigismund of Luxembourg, a member of the imperial Luxembourg dynasty, was already decided before her first birthday. A delegation of Polish prelates and lords confirmed her right to succeed her father in Poland in 1379.

Having no male siblings, Mary was crowned "king" of Hungary on 17 September 1382, seven days after Louis the Great's death. Her mother, who had assumed the regency, absolved the Polish noblemen from their oath of loyalty to Mary in favour of Mary's younger sister, Jadwiga, in early 1383. The idea of a female monarch remained unpopular among the Hungarian noblemen, the majority of whom regarded Mary's distant cousin, Charles III of Naples, as the lawful heir. To strengthen Mary's position, the queen mother wanted her to marry Louis, the younger brother of Charles VI of France. Their engagement was announced in May 1385.

Charles III of Naples landed in Dalmatia in September 1385. Sigismund of Luxembourg invaded Upper Hungary (now Slovakia), forcing the queen mother to give 14-year-old Mary in marriage to him in October. However, they could not prevent Charles from entering Buda. After Mary renounced the throne, Charles was crowned king on 31 December 1385, but he was murdered at the instigation of Mary's mother in February 1386. Mary was restored, but the dead king's supporters captured her and her mother on 25 July. Queen Elizabeth was murdered in January 1387, but Mary was released on 4 June 1387. Mary officially remained co-ruler with Sigismund, who had meanwhile been crowned king, but her influence on the government was minimal. She and her premature son died after falling from a horse when the queen went on a hunting trip while she was pregnant.

Mary was born in the latter half of 1371 to Louis the Great, King of Hungary and Poland, and his second wife, Elizabeth of Bosnia. She was the second daughter of her parents. They had been childless for over a decade before Mary's older sister, Catherine, was born in 1370. Mary and Catherine gained another sibling, Jadwiga, in 1374.

Since Louis had fathered no sons, the expectation that he would bequeath Hungary, Poland, and his claims to the Kingdom of Naples and Provence to his daughters made them desirable spouses for members of the European royal families. Before Mary's first birthday, her father made a promise to Charles IV, Holy Roman Emperor, that Mary would marry the emperor's second son, Sigismund of Luxembourg. Louis confirmed his promise in a deed in June 1373. Mary and Sigismund were closely related, because her paternal grandmother, Elizabeth of Poland, was the sister of his great-grandfather, Casimir III of Poland. Pope Gregory XI issued the dispensation necessary for their marriage on 6 December 1374. The leading Hungarian and Polish lords confirmed Louis's promise of Mary's and Sigismund's marriage on 14 pril 1375.

Mary's older sister, Catherine, who had been betrothed to Louis of France, died in late 1378. Louis the Great confirmed his earlier promise of Mary's and Sigismund's marriage to Sigismund's brother, Wenceslaus, King of the Romans, in Zólyom (now Zvolen in Slovakia) in 1379. Louis and Wenceslaus also agreed that they would acknowledge Urban VI as the lawful pope against Clement VII. Mary was formally engaged to Sigismund in Nagyszombat (now Trnava in Slovakia) in the same year. Sigismund, who had meanwhile become Margrave of Brandenburg, came to Hungary.

Louis summoned the Polish prelates and lords to Kassa (now Košice in Slovakia) in September 1379, persuading them to acknowledge Mary's right to succeed him in Poland. The contemporaneous Jan of Czarnków, who was biased against Louis, recorded that the Poles yielded to the monarch's demand only after he had prevented them from leaving the town by shutting its gates. At a meeting with Leopold III, Duke of Austria in early 1380, Louis strongly hinted that he would bequeath Hungary to his younger daughter, Jadwiga, who had been engaged to Leopold III's son, William. Upon Louis's demand, a delegation of the Polish noblemen again paid homage to Sigismund and Mary on 25 July 1382. According to the historian Oscar Halecki, Louis wished to divide his kingdoms between his two surviving daughters, but Pál Engel and Claude Michaud write that the ailing king wanted to bequeath both Hungary and Poland on Mary and Sigismund.

Louis the Great died on 10 September 1382. Cardinal Demetrius, Archbishop of Esztergom, crowned Mary "king" with the Holy Crown of Hungary in Székesfehérvár on 17 September, a day after her father's burial. Mary's title and her rapid coronation in the absence of her fiancé, Sigismund, show that her mother and her mother's supporters wanted to emphasize Mary's role as monarch and to postpone or even hinder Sigismund's coronation.