Recorded as O'Reilly, Reilly, Realy, Mac Grealy, and in County Mayo Grealy, Greally, and Greeley, this is an ancient Irish surname. It derives from the pre 10th century Gaelic personal name O'Raghailleach, of unknown origin. The surname is first recorded in surving registers in the late 16th century, (see below), but is clearly much older. Sadly most early registers were destroyed in 1922 when the then IRA in a fit of vandalism blew up the Public Records Office in Dublin, and burning most of the country's early heritage. Early exampls of the surname recordings include: Hugh O'Reilly, (1580 - 1653), John Reilly who married Elizabeth Barry on June 3rd 1689, at the church of St. Katherine by the Tower (of London), whilst Hugh O'Reilly was a political writer and master in chancery and clerk of the council of Ireland in James 11's reign (1685 - 1690). He accompanied the king into exile in Rome and whilst there published "Ireland's Case briefly stated" in 1695. John Greeley and Ellen Grealy both of County Mayo were "Famine Emigrants" to New York in 1846, as was Catherine Reilly, who sailed aboard the ship "Jane" on May 5th of that year. The first recorded spelling of the family name is shown to be that of Egan O'Rahilly of County Kerry, (1670 - 1726) and regarded as one of Irelands greatest poets. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.