Cahill is a surname of Irish origin, often associated with various notable individuals and families. It is derived from the Gaelic name O'Cathail, meaning "descendant of Cathal," which translates to "battle ruler." The name is common in Ireland and among the Irish diaspora around the world. In addition to being a surname, Cahill can refer to several places, such as Cahill Park in Australia. It is also the name of various businesses and organizations. The name has been used in popular culture, including characters in literature and film, contributing to its recognition beyond just a family name.