This interesting surname, chiefly found in the Connacht counties of Sligo and Galway, translates as "Son of the Devotee of (St.) Peter". The component elements of the name are the Gaelic prefix "mac", son of, plus "giolla" literally meaning "servant", but used here in the sense of "devotee", and the genitive case of the personal name Peadar i.e. Peter, ultimately from the Greek Petros, rock or stone. This name was extremely popular throughout Christian Europe in the Middle Ages, as it had been bestowed by Christ as a byname on the apostle Simon - "Thou art Peter and upon this rock I will build my church". Kilfeather, Kilfedder and Gilfedder are the chief Anglicized forms of Mac Giolla Pheadair. On May 25th 1846, Margaret Kilfeather, a famine emigrant to New York, embarked from Liverpool on the ship "Marmion" bound for that port. Maria Kilfeather and Johannes O'Connor were married in Calry Roman Catholic Church, County Sligo, on January 8th 1859. The first recorded spelling of the family name is shown to be that of Domhall Mac Giolla Pheadair, (christening), which was dated February 4th 1844, at Drumcliff and Magherow, Co. Sligo, during the reign of Queen Victoria, known as "The Great White Queen", 1837 - 1901. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.