Pope Saint Hyginus was Greek by birth but we don’t know when he was born. He was likely elected as the Bishop of Rome, and therefore Pope from 138 until his death in 140. About a year after Hyginus became pope, Marcus Aurelius was named Caesar of the Roman Empire. He disagreed with the Gnostic heresy promoted in Rome by Valentinus and Cerdo. He excommunicated both men to protect the integrity and avoid confusion in the Church. While he was Pope he instituted godparents at baptism to help the baptized during their Christian life. He also said all churches should be consecrated to God.
There seems to be some question about the order of the early Bishops of Rome, but Saint Irenaeus identified Saint Hyginus as the eighth successor of Satin Peter in his writing Against Heresy.