From Where Valentine's Day Comes From
Saint Valentine (in Latin, Valentinus) is the name of several martyred saints of ancient Rome. The name "Valentine", derived from valens (worthy), was popular in late antiquity.Of the Saint Valentine whose feast is on February 14, nothing is known except his name and that he was buried at the Via Flaminia north of Rome on February 14. It is even uncertain whether the feast of that day celebrates only one saint or more saints of the same name. For this reason this liturgical commemoration was not kept in the Catholic calendar of saints for universal liturgical veneration as revised in 1969. But "Martyr Valentinus the Presbyter and those with him at Rome" remains in the list of saints proposed for veneration by all Catholics.
In the Eastern Orthodox Church, Saint Valentine the Presbyter, is celebrated on July 6, and Hieromartyr Saint Valentine (Bishop of Interamna, Terni in Italy) is celebrated on July 30.
The name "Valentine" does not occur in the earliest list of Roman martyrs, compiled by the Chronographer of 354. The feast of St. Valentine was first established in 496 by Pope Gelasius I, who included Valentine among those "... whose names are justly reverenced among men, but whose acts are known only to God." As Gelasius implied, nothing was known, even then, about the lives of any of these martyrs. The Saint Valentine that appears in various martyrologies in connection with February 14 is described either as:
The first representation of Saint Valentine appeared in the Nuremberg Chronicle, (1493); alongside the woodcut portrait of Valentine the text states that he was a Roman priest martyred during the reign of Claudius II, known as Claudius Gothicus. He was arrested and imprisoned upon being caught marrying Christian couples and otherwise aiding Christians who were at the time being persecuted by Claudius in Rome. Helping Christians at this time was considered a crime. Claudius took a liking to this prisoner -- until Valentinus tried to convert the Emperor -- whereupon this priest was condemned to death. He was beaten with clubs and stoned; when that didn't finish him, he was beheaded outside the Flaminian Gate. Various dates are given for the martyrdom or martyrdoms: 269, 270, or 273.
May his prayers be heard on our behalf.