Vardan Mamikonian (c. 387 – 451) was an Armenian military leader who led a rebellion against Sasanian Iran in 450–451. He was the head of the Mamikonian noble family and holder of the hereditary title of sparapet, the supreme commander of the Armenian armed forces. Vardan and most of his comrades died at the Battle of Avarayr in 451, but their sacrifice was immortalized in the works of the Armenian historians Yeghishe and Ghazar Parpetsi. He is regarded as a national hero among Armenians and venerated as a martyr and a saint of the Armenian Church. Vardan and the rebellion he led are commemorated in numerous works of art and literature. According to Arshag Chobanian, "To the Armenian nation, Vartan [...] is the most beloved figure, the most sacred in their history, the symbolical hero who typifies the national spirit."

Vardan Mamikonian was born in approximately 387 in the settlement of Ashtishat in the Taron region to Hamazasp Mamikonian and Sahakanoysh, daughter of Patriarch Sahak of Armenia. He had two younger brothers, Hamazasp and Hmayeak. He was educated in Vagharshapat at the school founded by Patriarch Sahak and Mesrop Mashtots. After the death of his father, he became the head of the Mamikonian noble family. In 420, he went to Constantinople with Mesrop Mashtots and was appointed stratelates (general) of Byzantine Armenia by Theodosius II. In 422, he returned to Vagharshapat, then went to Ctesiphon, where Sasanian king Bahram V recognized him as sparapet of the Kingdom of Armenia; the office of sparapet, the supreme commander of the Armenian armed forces, was held hereditarily by the Mamikonian family. Vardan retained this title after the abolition of the Kingdom of Armenia in 428.

Conditions worsened in Sasanian Armenia with the accession of Yazdegerd II in 439. At first, Yazdegerd and his officials imposed heavier taxes and obligations on Armenia and its nobility, but did not yet openly move against the Armenian Church. In 442, Yazdegerd sent the Armenian cavalry commanded by Vardan east to fight the Huns. In 449, the Sasanian king issued an edict officially imposing Zoroastrianism on Armenia. That same year, the Armenian elite gathered at Artaxata under the presidency of marzpan Vasak Siwni, Vardan, the bidaxsh of the Iberia March, and the acting Catholicos of Armenia to declare their loyalty to the Sasanian state and their Christian faith. Yazdegerd did not accept this decision and summoned the Armenian magnates (nakharars) to Ctesiphon and forced them to convert to Zoroastrianism. Yazdegerd released most of the nobles after an unexpected attack from the east and sent magi to convert Armenia.

Upon their return to Armenia, Vardan and most of the Armenian nobles repudiated their conversion, although Yeghishe and Ghazar Parpetsi give conflicting accounts of Vardan's initial apostasy and the origins of the Armenian rebellion that broke out in 450. Vardan may have initially intended to retire into exile, but soon emerged as the leader the popular rebellion against the imposition of Zoroastrianism. Vardan and his allies made a solemn oath and captured a number of fortresses and settlements. Vardan's forces won a major victory over the Persians in the summer of 450 and secured an alliance with the northern Huns; however, an embassy to Byzantium asking for aid was unsuccessful. Vardan was opposed by a significant pro-Persian party of Armenian nobles, and marzpan Vasak Siwni refused to follow him out of Armenia to meet the Persians in battle.

In the summer of 451, a large Sasanian army including the elite cavalry corps of the Immortals and war elephants marched against the Armenian rebels. Vardan's army battled with the Persians at Avarayr near Maku on June 2. The supporters of Vasak Siwni deserted during the battle and Vardan's forces were defeated, with Vardan and most of the Armenian nobility dying in the fighting. The aftermath of the Battle of Avarayr is not completely clear, but it appears that Yazdegerd, alarmed by the Persian losses, withdrew his troops and imprisoned Vasak Siwni. Vardan's surviving supporters were imprisoned in Iran, although many of them were eventually released in the following years. In 481, a new rebellion manifested under the leadership of Vardan's nephew, Vahan Mamikonian, which succeeded in securing recognition of Armenian religious rights and autonomy with the Treaty of Nvarsak in 484.

Vardan Mamikonian was the father of Vardeni Mamikonian, known Shushanik, born around 439 AD. Shushanik married Varsken, a prominent Mihranid feudal lord (pitiakhsh). When Varsken took a pro-Persian position renouncing Christianity and adopting Zoroastrianism, he tried to force his wife Shushanik to convert as well, but she refused vehemently to submit and abandon her Christian faith, so she was put to death in AD 475 on her husband's orders. Shushanik has been canonized by the Georgian Orthodox and Apostolic Church and is venerated by the Armenian Apostolic Church. Known as Saint Shushanik, her feast day is celebrated on October 17.