Black Irish (folklore)
The historical term Black Irish was a myth most likely created and popularised in the 19th and 20th centuries by Irish-Americans to conceal interracial unions with African-Americans. It almost exactly parallels the phrase "Black Dutch" which was also used in the United States to hide racial identity, and is similar to a myth used by many families in the Southern United States who would  claim descent from a "Cherokee Princess" in order to conceal descent from African-Americans. Description
The Black Irish myth proposed that a strain of Irish people with black hair and dark complexions, referred to as "Black Irish", were the descendants of Spanish sailors shipwrecked during the Spanish Armada of 1588. In reality, of the roughly 5,000 Spanish sailors who were recorded as being wrecked off the coast of Ireland and Scotland, the very few that survived the wrecks were either hunted down and killed by English troops or immediately returned to Spain, and thus could not have impacted the Irish gene pool in any significant manner. In 1912, Irish author James Joyce asserted a different version of the myth, suggesting in an article that the residents of Galway were of "the true Spanish type" owing to their interaction and trade with the Spanish in the medieval era. Genetic studies
Two separate genetic studies carried out in the 2010s found little if any Spanish traces in Irish DNA, with population geneticist Dan Bradley of Trinity College Dublin, rejecting any notion of the "Black Irish" existing or having any genetic basis. Potential purposes of the myth
David Roediger, a professor of American studies and history with the University of Kansas, has suggested the myth of the Black Irish as the descendants of Spanish sailors was created and popularised in the 19th and 20th centuries by Irish Americans in the United States seeking to conceal interracial children produced with African Americans. Similarly, researchers into the multi-racial Melungeon ethnic identity and other Native American groups in the southern United States found that "Black Irish" was amongst a dozen myths about Spanish sailors and other European women used to disguise the African heritage of interracial children. A primary source told researchers "They would say they were "Black Dutch" or "Black Irish" or "Black French", or Native American. They’d say they were anything but Melungeon because anything else would be better ... because to be Melungeon was to be discriminated against." Modern use of the term
In the early to mid-20th century, the myth of the Black Irish was used occasionally by Aboriginal Australians in order to racially pass themselves into white Australian society. In the 1950s, Malcolm X of the Nation of Islam would occasionally assert, alongside claiming Italians were descended from Carthaginian Africans and the Spanish were descended from the Moors, that the Irish were also of Black descent by invoking the Black Irish myth. In the 21st century, "Black Irish" is now more commonly used to refer to Irish nationals of African descent. As of 2016, 10,100 Irish nationals of African descent living in the Republic of Ireland referred to themselves as "Black Irish" in the national census. Figures such as Phil Lynott are described by Irish national media sources as "Black Irish". References

American folklore
Irish folklore
Historical definitions of race
Irish-American history
Pseudohistory