Saint Flavian was a 5th-century Christian bishop of Constantinople. He is best known for his role in the Council of Chalcedon in 451 AD, where he defended the doctrine of the two natures of Christ—divine and human. His leadership during this council helped shape early Christian theology. Flavian faced significant opposition, particularly from the followers of Eutyches, who promoted a monophysite view that Christ had only one nature. After enduring persecution, Flavian was exiled and ultimately died from injuries sustained during a violent confrontation. He is commemorated as a martyr in the Christian tradition.