McClanahan is an Irish surname that is derived from several Anglicized forms of the Gaelic surname Mac Lennacháin or Mac Gille Onchon.
[2] The New Dictionary of American Family Names translates Mac Lennacháin as "the son of little Leannach" and Mac Gille Onchon as "the son of the servant of Oncho.
[2] Mac Lennacháin is sometimes written as MacClannachan, with variations including MacClenaghan, McClenaghan, M'Clenaghan.
[4] Gille is a Gaelic word meaning "servant", more specifically a professional guide for sportsmen, especially in fishing and deerstalking.
[5] The family motto, as recorded in the McClanahan coat of arms, is "Virtue Is My Honor.