This very rare surname is of Irish origin, and is an Anglicized form of the Gaelic Mac Riagain, the prefix "mac" meaning son of, plus the personal name "Riagan" of uncertain origin, perhaps aking to "riodhgach" meaning impulsive, furious. The surname appeared occasionally in medieval and early modern records in east Leinster; however, due to the destruction of many early Irish records, exact examples have been lost. The name is rare now and seldom found outside Leinster. Variations in the spelling of the surname include Greggan, Gregon, and Gregine. Church Records list the christenings of Sarah, daughter of John and Ann Gregan, on the 8th September 1765, and their son John on the 26th July 1767, both at St. Giles, Cripplegate, London. Joseph, son of Michael and Mary Gregan, was christened on the 6th January 1865 in Dublin. One John Gregan, aged 20 yrs., a famine emigrant, sailed from Liverpool bound for New York on March 13th 1846. The first recorded spelling of the family name is shown to be that of Thomas Gregine, which was dated 13th April 1578, married Brigitte Somer, at St. Margaret's, Westminster, during the reign of Queen Elizabeth 1, known as "Good Queen Bess", 1558 - 1603. 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.