The feast of St Pachomius (circa 272-348) is celebrated in the modern Benedictine calendar today (May 15); in the 1962 calendar is memorial is May 14. He is an important saint for monastics, as the author of the first known rule for coenibites (monks living in community).
Saint Pachomius was born in Egypt to pagan parents and was forced to become a soldier at age 21. In this capacity he encountered a group of Christians ministering to the troops, and was so impressed by them that he decided to investigate the faith once he had left the army. He was duly converted and baptised, and initially sought the guidance of a hermit named Palaemon. After a few years he set out to live near St Antony, whose practices he imitated until Pachomius heard a voice in Tabennisi that told him to build a dwelling for the hermits to come to. He established his first monastery 318 and 323, and the community grew rapidly, and made several new foundations.
You can read a life of the saint, translated from the Greek into Latin by one of St Benedict's contemporaries, Dionysius Exiguus, here.