Casey is a given name, originally derived from the Irish Gaelic cathasaigh, meaning "vigilant" or "watchful"[dubious – discuss].
[1] Kayce, a spelling variant, ranked 587th for American newborn boys on the U.S. popularity chart in 2022.
The increase in usage of the name was inspired by the popularity of the television series Yellowstone that is set in modern-day Montana and of its spinoffs, 1883 and 1923, about ancestors of the family.
[2] Place name Kaycee, Wyoming uses another spelling variation.
Some other spelling variants in use for both sexes include Cacey, Caci, Caicey, Casi, Cayce, Ceysee, Kacey, Kacee, Kejsi, KC, Kaci, Kasi, Kacy, Kacie, Kaisey, Kasey, Kasie, Kaycey, Kaycie, Kayci, Kaycie, Kaysee, Kaysey, Kaysi, Kaysie, and Keize.