The name might have various forms, among them - Horgan, Horrigan, Horegan, Hourigan, Organ, Howregan. Some men called Harrigan appear to belong to this group.
Hor(ri)gan, Hanrahan, and Hourihane share similar heraldry but genetic evidence shows that they are distinct from each other.
Most Cork Hor(ri)gans identified so far are thought to be descended from the Lagin (Irish Sea) people. They carry the yDNA mutation R-Z255, which split into two branches, R-BY2853 and R-BY45179, some time in the second millennium.