Casey is an Irish surname, from the Gaelic O Cathasaigh, meaning "descendant of Cathasach", a byname for someone "vigilant" or "watchful". In American folklore it belongs to the railroad engineer Casey Jones and to the slugger in the poem Casey at the Bat. Casey ranked 193rd in 2000, sank to number 555 in 2015 and has rebounded strongly since, to 320th place among boys' names in 2025.