The following was extracted from Irish Families, Their Names, Arms and Origins originally compiled by Edward MacLysaght and published in 1957 by Hodges Figgis & Co. Ltd. of Dublin. It appeared in the Sep. 1996 edition of Coffey Cousins' Clearinghouse newsletter and was submitted to that publication by Tom Veale.
In Irish this name is O'Cobhthaigh pronounced O'Coffey in English: It is probably derived from the word cobhthach meaning victorious. Coffey is one of those surnames which have not resumed the prefix O, dropped during the period of Gaelic submergence. Several distinct septs were prominent in medieval times, of which two are still well represented in their original homeland. These are O'Coffey of Corcalaoidhe in south-west Co. Cork, where local pronunciation often makes the name Cowhig or Cowhey, as in the place name Dunocowhey, called after them. This sept is the same stock as the O'Driscolls.
A second minor sept was a branch of the O'Maddens of Ui Ma'ine, whose descendants are found to-day in Co. Roscommon.
A third, once of considerable importance but now scattered, belonged to Co. Westmeath where they were famous as a bardic family.
The more recent times the Leinster Coffeys are represented by Charles Coffey (1700-1745), dramatist and actor, the first to introduce Irish airs in a play. George Coffey (1857-1916), the archaeologist, though his family has long associations with Dublin, was descended from the Munster sept. The place-name Rothcoffey occurs both in Co. Kildare and Co. Leix.