The name CRATLOE is derived from the gaelic CREAT-SHAILEÓG, meaning the sallow wood, or the land of sallow trees. At one stage the Cratloe Woods were famous for primeval oak woods. In the ninth century the Ulstermen invaded the MacNamara territory and carried home oak timbers to roof the Royal palace of Aileach near Derry. Cratloe also supplied the oak beams for the roof of Westminster Hall, London and the Royal Palace in Amsterdam. In 1215 Geoffrey Lutterel was granted "the land of Crateluach" by King John for thirty ounces of silver. From that time the great woods of Cratloe were gradually cut away. In more recent times an 800 acre state forest has been planted on the slopes of Woodcock Hill.

Cratloe could also take its name from "CROIT-SHLIABH", the humped-back mountain. From Gallows Hill this description appears to have a certain logical aptness. Cratloe's importance stems from the fact that it was one of the major passes on highways from Munster into Connacht as the hills to the north, and the Shannon to the south, rendered these routes inaccessible.

The area of Cratloe was mentioned by the Four Masters as far back as 379 A.D. In the year 365 A.D. Eoghy, who was King of Ireland, died at Tara. His son Brian was too young to reign so Eoghy's wife's brother assumed the throne. He was Crimhthan, King of Munster. By 379 A.D. Crimhthan's sister decided that the throne should revert to her son Brian. She administered poison to her brother, Crimhthan. His career was thus ended while he was on a journey through Clare. He died in 379 A.D. near Cratloe on the mountain called "Slieve-Oighe an Righ", meaning The Hill of the King's Death. Brian, however, had to settle for the crown of Connacht while Crimhthan's son Niall, by his second wife, became King. Niall later became known as Niall of the Nine Hostages.

Cratloe is next mentioned in 1510 when an English and Irish army led by Gearóid Fitzgerald, Earl of Kildare and Justice of Ireland, marched into Thomond. They were opposed by Toirdhealach, son of Tadhg O'Brien, Lord of Thomond, supported by the MacNamara, Sil-Aedha and Clanrickard, at Móin na mBráthar, near Cratloe. "O'Briens army attacked the foreign horde and killed Baron Kent and Barnwall Kircustown and innumerable other noblemen. The foreigners escaped by flight and O'Briens forces returned with great spoil."

Some fifty years later however, the residents of this area had become somewhat disenamoured of the Earl when he made incursions into their lands in order to procure cattle to pay his gallóglaigh. "The country rose up against him on every side from Sliabh Oidheadha an Righ to Luchat and from Rinnanna to Scarriff. They overtook the Earl and slew nearly one hundred of his men at this time. (1564)."

In 1837 Cratloe rated only a brief mention in Lewis Topographical Dictionary under the heading "Killfentinan." The account tells us that "a court for the manor of Bunratty is occasionally held at Cratloe, by Lord Egremont's seneschal, in which small debts are recoverable. The Roman-Catholic parish is co-extensive with that of the Established Church. The principal chapel is at Cratloe Cross. Application is about to be made to establish a school at Cratloe, under the National Board."