Kehoe, originally spelled MacKehoe (from Irish Mac Eochaidh 'son of Eochaidh', a personal name based on each 'horse'), is an Irish surname that stems from several distinct septs in Ireland.
The most notable branch were from southeastern Ireland in the province of Leinster and are descended from Brandub mac Echach, King of Leinster, in the 6th century AD. This branch were the Chief Filí of Leinster up until the 17th century and inaugurated the Kings of Leinster upon their stone called Leac Mhic Eochadha ("Eochaidh's flagstone").
Another unrelated and separate branch, descends from King Domnall Mór Ua Cellaigh of the O'Kellys of Uí Maine, who died in 1221.
Many of their descendants have emigrated to America and have spread throughout that part of the world. The name is spelled in a variety of ways, however the most common are Kehoe, Keogh and Keough. In Ireland the Kehoe version is used most often in and around County Wexford while Keogh is more common throughout the rest of the country.