Recorded in many spelling forms including Gaughan, Gavan, Gavaghan, Gavahan, Gahan, O' Geehan, MacGeehan, McGeehan, and McGahan, this notable surname is Irish. Originally it was exclusive to the province of Connacht, but is now quite popular in parts of Ulster. 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 as O'Gaughan was 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, whilst it is as Gahan in East Leinster, Gavahan or Gavaghan in County Roscommon, McGeehan and Mageen in County Donegal, and McGahan in County Louth. Early examples of surname recordings taken from the Famine Lists and surviving church registers include: Patrick McGeehan who left Liverpool, on the ship "Monetzuma" bound for New York on May 15th 1846, Susan Gavaghan, who also left for New York on the ship "New-York" 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. Throughout the centuries surnames in every country have continued to "develop", often leading to astonishing variants of the original spelling.