The breed is very old; there are suggestions it may have been brought to Ireland as early as 7000 BC. These dogs are mentioned, as cú (variously translated as hound, Irish hound, war dog, wolf dog, etc.) in Irish laws and in Irish literature which dates from the 5th century or, in the case of the Sagas, from the old Irish period - AD 600-900. The word "Cú" often became an added prefix of respect on the names of warriors as well as kings denoting that they were worthy of the respect and loyalty of a Cú.
Ancient artworks and writings have encouraged modern authors to imagine their existence as a breed by 273 BC. However, there is indication that large dogs may have existed even as early as 279 BC when the Tectosages and Tolistobogii Celts sacked Delphi. Survivors left accounts of the fierce Celts and the huge dogs who fought with them and at their side. They were mentioned by Julius Caesar in his treatise, The Gallic Wars, and by 391 AD, they were written about by Roman Consul, Quintus Aurelius Symmachus, who received seven of them, "canes Scotici", as a gift to be used for fighting lions and bears, in his words, "all Rome viewed (them) with wonder".
Wolfhounds were bred as hunting dogs by the ancients, who called them Cú Faoil. The Irish continued to breed them for this purpose, as well as to guard their homes and protect their stock. Cúchulain, a name which translates literally as "hound of Culain", gained his name when as a child, known then as Sétanta, when he slew the ferocious guard dog of Culain, forcing him to offer himself as a replacement. During the English Conquest of Ireland, only the nobility were allowed to own Irish Wolfhounds, the numbers permitted depending on position. They were much coveted and were frequently given as gifts to important personages and foreign nobles. Wolfhounds were the companions of the regal, and were housed themselves alongside them. King John of England, in about 1210 presented an Irish hound, Gelert, to Llewellyn, a prince of Wales. The poet The Hon William Robert Spencer Immortalized this hound in a poem.
In his History of Ireland completed 1571, Edmund Champion gives a description of the hounds used for hunting the wolves on the Dublin and Wicklow mountains. He says: They (the Irish) are not without wolves and greyhounds to hunt them, bigger of bone and limb than a colt. Due to their popularity overseas many were exported to European royal houses leaving numbers in Ireland depleted. This led to a declaration by Oliver Cromwell himself being published in Kilkenny on 27 April 1652 to ensure that sufficient numbers remained to control the wolf population.
References to the Irish Wolfhound in the 18th century tell of its great size, strength and greyhound shape as well as its scarcity. Writing in 1790, Bewick described it as the largest and most beautiful of the dog kind; about 36 inches high, generally of a white or cinnamon colour, somewhat like the Greyhound but more robust. He said that their aspect was mild, disposition peaceful, and strength so great that in combat the Mastiff or Bulldog was far from being an equal to them. The last wolf in Ireland is thought to have been killed at Myshall, on the slopes of Mount Leinster in Co. Carlow in 1786 by a pack of wolfdogs kept by a Mr Watson of Ballydarton. The remaining hounds in the hands of a few families who were mainly descendants of the old Irish chieftains, were now symbols of status rather than hunters, they were said to be the last of their race.
Scotsman Captain George Augustus Graham is responsible with a few other breeders for attempting to reaffirm the breed's existence. In 1879 he wrote: "It has been ascertained beyond all question that there are few specimens of the breed still left in Ireland and England to be considered Irish Wolfhounds, though falling short of the requisite dimensions. This blood is now in my possession." Captain Graham devoted his life to ensuring the survival of the Irish Wolfhound. Owing to the small numbers of surviving specimens outcrossing was used in the breeding programme. It is believed that Borzoi, Great Dane, Scottish Deerhound and English Mastiff dogs all played their part in Graham's creation of the dog we currently know. The famous English Mastiff Garnier's Lion was bred to the Deerhound Lufra, and their offspring Marquis enters Wolfhound pedigrees through his granddaughter Young Donagh. Graham included "a single outcross of Tibetan Wolf Dog". This was long assumed to have been a Tibetan Mastiff. However, a photograph of "Wolf" shows a bearded, long-coated dog—what would now be called a "Tibetan Kyi Apso" or "dokhyi apso". In 1885 Captain Graham with other breeders founded the Irish Wolfhound Club, and the Breed Standard of Points to establish and agree the ideal to which breeders should aspire.
The Wolfhound was historically a dog that only nobles could own and was taken up by the British during their rule in Ireland. This made it unpopular as a national symbol and the Kerry Blue Terrier was adopted by Republicans such as Michael Collins.The Wolfhound has been adopted as a symbol by both rugby codes. The national rugby league team is nicknamed the Wolfhounds, and the Irish Rugby Football Union, which governs rugby union, changed the name of the country's A (second-level) national team in that code to the Ireland Wolfhounds in 2010.