The Hilandar Monastery (/ˈhɪləndər/, HIL-lin-dər, Greek: Μονή Χιλανδαρίου, romanized: Moni Chilandariou, Serbian: Манастир Хиландар, romanized: Manastir Hilandar) is one of the twenty Eastern Orthodox monasteries in Mount Athos in Greece and the only Serbian Orthodox monastery there.

It was founded in 1198 by two Serbs from the Grand Principality of Serbia, Stefan Nemanja (Saint Symeon) and his son Saint Sava. St. Symeon was the former Grand Prince of Serbia (1166–1196) who upon relinquishing his throne took monastic vows and became an ordinary monk. He joined his son Saint Sava who was already in Mount Athos and who later became the first Archbishop of Serbia. Upon its foundation, the monastery became a focal point of the Serbian religious and cultural life, as well as assumed the role of "the first Serbian university". It is ranked fourth in the Athonite hierarchy of 20 sovereign monasteries.

It is regarded as the historical Serbian monastery on Mount Athos, traditionally inhabited by Serbian Orthodox monks. The Mother of God through her Icon of the Three Hands (Trojeručica) is considered the monastery's abbess. The monastery contains about 45 working monks.^[when?]

The etymological meaning of "Hilandar" is probably derived from the Greek word chelandion, which is a type of Byzantine transport ship, whose skipper was called "helandaris".

The monastery was founded in 1198; prompted by the Mount Athos monastic community, Byzantine Emperor Alexios III Angelos (1195–1203) issued a golden sealed chrysobull donating the ancient monastery Helandaris, "to the Serbs as an eternal gift...," thereby designating it, "to serve the purpose of accepting the people of Serbian descent, who seek to pursue the monastic way of life, as monasteries belonging to Iberia and Amalfi endure on the Mount, exempt from any authority, including the authority of Protos." Hilandar was thereby handed over to Saint Sava and Saint Symeon with the mission of establishing and endowing a new monastery, elevated to the imperial rank. Since then, the monastery became a cornerstone of the religious, educational and cultural life of Serbian people.

Upon securing Serbian authority within the monastery, Saint Sava and Saint Symeon jointly constructed the monastery's Church of the Entry of the Lady Theotokos into the Temple between 1198 and 1200, while also adding Saint Sava's Tower, the Kambanski Tower, and Saint Symeon's monastic chambers - cells. Saint Symeon's middle son and Saint Sava's older brother, Serbian Grand Prince Stefan "the First-Crowned" King provided financial resources for this restoration. As Hilandar's founder, Saint Symeon issued a special founding charter or chrysobull, which survived until World War II, when it was destroyed as a result of the Operation Punishment and the notorious April 6, 1941 Nazi Germany bombing of Belgrade that leveled to the ground the National Library of Serbia building in Kosancicev Venac. Following 1199, hundreds of monks from Serbia moved to the monastery, while large pieces of land, metochions and tax proceeds from numerous villages were provided to the monastery, especially from the Metohija region of Serbia.

Saint Symeon died in the monastery on February 13, 1200, where he was buried next to the main church of the Entry of the Lady Theotokos into the Temple. His body remained in Hilandar until 1208 when his myrrh-flowing remains were transferred to Serbia and interred into the mother-church of all Serbian churches the Studenica Monastery according to his original desire, which he previously completed in 1196. Following the relocation of Saint Symeon's remains, what would eventually become world-famous grapevines began growing on the spot of his old tomb, which gives to this day miraculous grapes and seeds that are shipped all over as a form of blessing to childless married couples. Following his father's death, Saint Sava moved to his Karyes hermitage cell, where he finished the writing of the Karyes Typikon, a book of directives, which shaped the eremitical monasticism all across the Serbian lands. He also wrote the Hilandar Typikon regulating spiritual life in monasteries, organization of services and duties of monastic communities. The Hilandar Typikon was modeled in part after the typikon of the Monastery of Theotokos Evergetis in Constantinople.

After the Fourth Crusade and Crusaders' sack of Constantinople in 1204, the whole Athos came under the Latin Occupation which exposed the Athonite monasteries to an unprecedented pillage. As a result, Saint Sava travelled to Serbia to secure more resources and support for the monastery. He also undertook a voyage to the Holy Land where he visited The Holy Lavra of Saint Sabbas the Sanctified in Palestine. There he received Hilandar's most revered relic, the miraculous icon of the Three-handed Theotokos (Trojeručica) painted by St. John of Damascus. According to St. John of Damascus' last will, he ordered the Mar Saba monastery brethren to add this miraculous icon to the old prophesy made by the monastery's founder Saint Sabbas the Sanctified. Saint Sabbas the Sanctified adjured his monks centuries earlier to donate the icon of the Milk-feeding Theotokos and his hegumen cane to the "namesake monk of royal blood from a faraway land" who would experience, during his pilgrimage to the monastery, the fall of his hegumen cane to the floor, previously affixed above his grave, while venerating icons and praying on that spot.