Killeen is an uncommon given name of Irish origin. It is derived from the Irish surname "Ó Ceallacháin," which means "descendant of Ceallachán." The name originally referred to a person who was cheerful, lively, or full of life. Killeen has been used as both a first and last name in Ireland for centuries but remains relatively rare outside of its native country.
The name Kileen experienced a decline in popularity between 1968 and 1988, with only five births recorded in the latter year compared to six in the former.