Black Irish is a traditional term believed to have originated in the United States that commonly ascribes to a dark brown or black hair phenotype appearing in persons of Irish descent. It can be distinguished in contrast to the (lighter) brown, blond or red hair color variant, the latter stereotypically perceived by many to solely personify the look of typical Irish folk. The term itself is rather ambiguous and not frequently used in everyday conversation. As such, the description of those it depicts has been known to vary to a degree in that some have differing views on which physical characteristics (e.g., dark hair, brown eyes, medium skin tone or dark hair, blue eyes, pale skin tone) better define the appearance of the so-called Black Irish. (see talk page)

Inspired by a myth which claims the darker features to be of Iberian derivation, some have looked to science for answers often citing genetic studies pertaining to those with Irish (and/or British) ancestry as a means of determining what genotypic and environmental factors have contributed to the divergence between the more and less prevalent types found amongst the Irish people.