Kelly comes from the Irish surname Ó Ceallaigh, descendant of Ceallach, a name of uncertain meaning, usually explained as "bright-headed" or "warrior". Actress Grace Kelly, who became Princess of Monaco, turned the surname into one of the most popular girls' names in America from the 1960s to the 1980s. Kelly was number 111 in 2000 and has gradually fallen to number 852 among girls in 2025.