There are approximately 50,000 Kellys and O'Kellys in Ireland today. It is the second most common Irish surname, not far behind Murphy in numerical strength. This name presents a remarkable example of the extent to which the prefixes O and Mac, so widely dropped during the period of Gaelic submergence, have been resumed. In the year 1890 there were 1,242 births registered as Kelly (distributed all over the country), while only nine were registered as O'Kelly. Today the proportion has risen from one in 130 to approximately one in twenty. President of Ireland, Mr. Sean T. O'Kelly, was a case in point.

There is a fairly widespread but quite erroneous belief that all persons of the name descend from members of the great O'Kelly sept of Uí Maine. The fact is that this surname came into being independently in at least seven widely separated places. Up to the thirteenth century the O'Kellys of Breagh (Co. Meath) were equal in importance to those of Uí Maine, but the impact of the Anglo-Norman invasion dispersed them. The Kellys of Ulster today are, no doubt, mostly of the O'Kelly of Cinel Eachrach sept (Counties Antrim and Derry); those of the midlands come probably from the O'Kellys, one of the seven septs of Leix who were still strong in their homeland in 1543, when they were specifically mentioned in an order relating to martial law in Queen's County; the atrocious murder of Fergus O'Kelly of Leix by the Earl of Kildare later in the same century, and the subsequent transfer of O'Kelly estates to the Fitzgeralds makes a black page in the history of the latter family; north Connacht Kellys are more likely to be of the Templeboy (Co. Sligo) sept than of that of Uí Maine; while Dublin Kellys can either be from a north Wicklow family of the name, or migrants from any of the above septs.

In each case the eponymous ancestor was called Ceallach, a personal name, from the genitive case of which we get O'Ceallaigh, the Irish form of the surname. The Kellys of Kilkenny and Tipperary, however, are O'Caollaidhe, not O'Ceallaigh, some of whom retain the older form Kealy, which is Queally in Co. Waterford. Queally is also found as a synonym of O'Cadhla, usually O'Kelly in English. Most Rev. Malachy Queally, who was among the most distinguished of the Archbishops of Tuam (1630-1645), was born in the diocese of Killaloe which includes a great part of Tipperary.

O'Kelly of Uí Maine was, and is, outstanding among all these. The first bearer of the name among this sept was Ceallach, son of Finnachta, a chief of the Hy Many people in about 874. Ceallach means war or contention. These O'Kellys were for centuries one of the most powerful Connacht families. They ruled over 80,000 acres of Hy Many, an area named for a fourth century invader from Ulster known as Maine Mór. Hy Many country, counties Galway and Roscommon, was once known as "O'Kelly's Country". Their chieftain in 1014, Tadgh Mór O'Ceallaigh, was killed at the battle of Clontarf when Brian Boru defeated the Vikings. The enfield, a strange heraldic beast borne as the crest on the armorial shield of some of the O'Kellys, is said to have come out of the sea at Clontarf to protect Tadgh Mór's body until his kinsmen could collect it for honourable burial. St Grellan, a contemporary of St Patrick, was their patron saint, and his crosier, lost comparatively recently, was always used as their battle standard. The Four Masters and the other Annals are full of their exploits and obituaries. Four of them have been Bishops of Clonfert, which is the diocese comprising much of the O'Kelly country. There is an authentic pedigree of their chiefs from the earliest times until the present day, and O'Kelly of Gallagh is one of the few whose claim to the designation Chief of the Name is officially recognised: in popular parlance he is The O'Kelly.

Although they lived up to their warlike reputation, the O'Kellys were also constructive. Conor O'Kelly, their chief for forty years, endowed thirteen churches, including, in 1167, O'Kelly's Church at Clonmacnoise. Traces of their many castles can be seen at Aughrim, Garbally, Gallagh (i.e. Ceallach), Monivea, Moylough, Mullaghmore, Castlekelly and Screen. The Abbey of Kilconnell, near Ballinasloe, County Galway, was founded in 1400 by an O'Kelly, and there the legendary enfield can be seen carved on many of their tombstones.

In 1351, William Boy O'Kelly, Chief of Hy Many, sent an invitation to all poets, musicians, jesters and artists to join him in a feast at the Castle of Galway which he had built himself on Galway Bay. This lavish feast was such a success that it was called "the welcome of all welcomes". Since then, "O'Kelly's Welcome" has come to mean great hospitality. In the fifteenth century, Murtough O'Kelly, Archbishop of Tuam, County Galway, commissioned the compilation of The Book of the O'Kellys, an amazingly comprehensive manuscript synchronising the reigns of Roman emperors and Irish kings. It is preserved in the Royal Irish Academy.

Malachy O'Kelly, who succeeded as the 28th Chief of Hy Many in 1499, was greatly angered when his newly-built castles at Monivea and Garbally were destroyed by the Earl of Clanrickard. He called on Garret Mór, the great Earl of Kildare, to help him to get his revenge. Garret Mór went willingly because of Clanrickard's ill treatment of his wife, Kildare's daughter. All the principal chiefs joined in - some on O'Kelly's side, others on Clanrickard's. On the Kelly side were O'Donnell, O'Neill, MacMahon, O'Hanlon, Magennis, O'Reilly and O'Farrell. In opposition, Ulick Burke, Earl of Clanrickard, had the O'Briens, MacNamaras, O'Carrolls and O'Kennedys. For the first time in Ireland gunpowder was used, and in 1504, at Knocktoe near Galway City, Clanrickard was horribly defeated. This lamentable inter-clan fighting, when some 10,000 Irish men faced one another in battle, contributed significantly to the later downfall of native Irish supremacy. Together they could probably have wiped out the English usurpers. Instead, the wily English regarded it as a great victory for them and awarded Kildare the Garter!

In 1583, an O'Kelly, with the assistance of Owen O'Moriarty, cut off the head of the old and ailing Earl of Desmond and sent it to Queen Elizabeth who spiked it on London Bridge. However, it was O'Moriarty who got the £1,000 reward in silver!

In 1518 the O'Kellys were one of the dangerous Irish septs named by the Corporation of Galway. In the next century the O'Kellys of Co. Galway were very prominent, as indeed were those of the Pale, too, for no less than ten of the name in Counties Dublin, Kildare and Meath were attainted in 1642.

It should be added that some Kellys are MacKelly, not O'Kelly. This was a minor sept also of east Connacht, but the Mac prefix is now entirely lost and any surviving modern representatives are thus indistinguishable from O'Kellys.

Coats of Arms:

O'Kelly (Uí Maine) Arms: Azure a tower triple-towered supported by two lions rampant argent as many chains descending from the battlements between the lions' legs or. Crest: On a ducal coronet or an enfield vert. Motto: Turris fortis mihi Deus [God (gave) to me a strong tower]

Though the records indicate that there were several septs of O'Kelly in Ireland, I can find no record of any Irish (O)Kelly coat of arms that is not identical or similar to the above famous armorial bearings.

Other Kelly arms (non Irish) include

Kelley, Keylley or Kelly (no location given). Arms: Or on two bars sable between three billets gules two and one, five martlets three and two of the first. Crest: A boar passant or wounded by an arrow proper.

Kelly (Kelly, Devonshire, England) Arms: Argent a chevron between three billets gules. Crest: Out of a ducal coronet gules an ostrich's head argent holding in the beak a horseshoe or.

Kelly (Scotland) Arms: Or a saltire sable between four fleurs-de-lis azure. Crest: None recorded.

Kelly (William Henry Kelly of Porchester Terrace, Paddington, Middlesex, England) Arms: Or a lion rampant azure between two flaunches of the last each charged with a castle of the first. Crest: In front of two anchors in saltire sable a castle or. Motto: justum perficito nihil timeto. Remark: These arms may have been derived from the famous Irish Kelly arms, but that is by no means certain.