Recorded in several spelling forms including Gaughan, Gavan, Gavaghan, Gavahan, and Gahan, this notable surname is Irish. Originally it was exclusive to the province of Connacht. The derivation is from the pre 10th century Old Gaelic "O'Gaibhtheachain", meaning the descendant of Gaibhtheachan, a male give name meaning fierce or dangerous! Traditionally, Irish family names are taken from the first head of the tribe, who was usually an illustrious warrior, which was clearly the case here. The first recorded spelling of this family name is in the ancient population group of Ui Fiachrach, located in north Mayo and Sligo, where they possessed territory in the Crossmolina area of County Mayo. The ancient Annals of the Four Masters mention them frequently as chiefs of Calry in the barony of Tirawley. The original Gaelic was later abbreviated to "O'Gachain, and other anglicized forms include: Gahan in East Leinster, and Gavahan or Gavaghan in County Roscommon. Early examples of surname recordings taken from Famine and surviving church registers include: Susan Gavaghan, who left for New York on the ship 'New-York of Liverpool' on November 6th 1846, and Honor Gaughan, the daughter of James Gaughan and Margaret Browne, who was christened at Crossmolina, on July 19th 1864, whilst quite recently on June 11th 1972, Patrick Gaughan and Mary Breda Hinchin were married in London. Surnames became necessary when governments introduced personal taxation. Throughout the centuries surnames in every country have continued to "develop", often leading to astonishing variants of the original spelling.