Gráinne Ní Mháille (aka Gráinne Mhaol, or “Granuaile”) stands out as a unique figure in Irish History and national symbolism; her fame and remarkable popularity come from the exceptional life she led, in exceptional circumstances: she was not only a chieftain, with a political and military role to play in troubled times for Ireland, under the reign of Elizabeth I of England, whom she met on a very public occasion in London, at Greenwich Castle. She was also at the head of a fleet that raided forts and garrisons in the West of Ireland and plundered local kingdoms. As a result, she was soon perceived to be “larger than life” and gave rise to numerous myths and symbols. As she was the product of a period when nationalism was largely unknown, this article will analyse the conjunction of historical facts and the birth of a national legend, to be found in a vast reservoir of myths that are part and parcel of the Gaelic heritage. Then the avatars of those myths, largely shaped according to political and military circumstances, will be examined and put into perspective. Part one will focus on Granuaile’s biography in relation to the role women were given in Gaelic society, in the field of matrimony, lineage and political power. Against all odds, Grace O’Malley managed to get some political recognition, as illustrated by the numerous battles she wedged against the most powerful representatives of English authority and her meeting with the Queen of England in 1597. Part two will be devoted to the mythological features of female Sovereignty and warfare (with the figures of the mythical Queen Medb and the warlike Mórrígu) that were gradually associated with Granuaile and form the basis of the legend that took shape throughout Irish history and political poems and songs, particularly when Ireland was struggling to shake off England’s grip on its political destiny. Such phenomenon is clearly exemplified in the 18th century with the adhesion of the Irish aristocracy to the cause of the Stuarts in the war of succession to the English throne, followed by the revolutionary uprising of 1798 called ‘the Year of the French’, then in 1916 with the Easter Rising, and the preponderant role of streets ballads and songs of rebellion.