This is an Irish surname. Recorded in several forms as shown below, it is a form of the original Gaelic name O' Daighre. This means literally the male descendant of the fiery chief! The surname is widespread in Ulster and North Connacht, particularly Derry, where it was borne by a notable ecclesiastical family. The name as Derry or Deary may derive from O' Daighre, but can also be from O' Doireidh, which has an unproven origin. More confusion arises because both names were originally located in the same area of North West Ulster; the O' Daighre being of Derry Church, with the O' Doireidh being of Donaghmore. Examples of recordings include Denis O' Diera, the bishop of Mayo from 1574 to 1576, whilst the Hearth Tax rolls for Armagh and Monaghan (1663-1666) often record the name as O' Deery and O' Deary. Father Patrick O' Deary was a friar of Derry Abbey, and especially mentioned by St. Oliver Plunket to be an exceptionally good man and a great preacher. Edmond Deery, aged 23 years, and a farmer, was a famine immigrant who left Dublin aboard the ship "Victory" bound for New York on May 21st 1847. The first recorded spelling of the family name is shown to be that of Maeliosa O' Doireidh, bishop of Columbkil. This was was dated circa 1300, in the Ancient Irish Records. Surnames became necessary when governments introduced personal taxation. This was sometimes known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.