Gannon is an Irish surname, an anglicized form of Mag Fhionnáin, "descendant of Fionnán", a name built on fionn and meaning "fair" or "white-haired". It rose in the United States alongside other Irish surnames like Brennan and Keegan, and the video game villain Ganon kept it in young ears. Gannon entered the top 1000 in 2002 and climbed to number 414 in 2014, but has dropped out again and ranks 2216 in 2025 with 64 births.