St. Apollinaris, a revered figure in the Catholic Church, is believed to have been a bishop of Ravenna, Italy, during the 1st century AD. He is recognized as one of the early Christian martyrs, with his feast day celebrated on July 20. According to tradition, St. Apollinaris was a disciple of St. Peter, who appointed him as the first bishop of Ravenna. 

His life was marked by his steadfast dedication to spreading the Christian faith and his role in establishing the church in that region. He faced severe persecution for his beliefs, ultimately leading to his martyrdom. The accounts of his life describe miraculous healings and his commitment to prayer and the sacraments. St. Apollinaris is often depicted in art holding a palm branch, symbolizing martyrdom, and is venerated as the patron saint of Ravenna and its archdiocese. His legacy continues to inspire devotion among Catholics today.