Saint Flavian of Constantinople was a prominent Christian leader in the 5th century, serving as the Patriarch of Constantinople from 446 until his death in 449. He is best known for his opposition to the teachings of Eutyches, which promoted a monophysite view of Christ, asserting that Christ had only one divine nature. Flavian defended the doctrine of the two natures of Christ, both divine and human, which was a key issue in early Christian theology. Flavian's commitment to orthodox beliefs led to his condemnation at the Robber Council of Ephesus in 449, where he was unjustly deposed and mistreated. He later died from the injuries sustained during this council. Flavian is venerated as a saint in both the Eastern Orthodox Church and the Roman Catholic Church, with his feast day celebrated on February 18.