Cahill

Cahill is a surname of Irish origin, derived from the Gaelic O Cathail, meaning "descendant of Cathal." The given name Cathal is believed to derive from elements meaning "battle" and "valor" or "bravery." The surname has a long-standing presence in Ireland and is now found throughout the Irish diaspora, with communities in the United States, the United Kingdom, Canada, and Australia. Variants and Anglicizations have occurred over time, contributing to a range of spellings in historical records.

Notable people with the surname Cahill include Tim Cahill, born 1979, an Australian international footballer known for his play with Everton and the Socceroos, and Eddie Cahill, born 1978, an American actor recognized for roles in television series such as Friends and CSI: NY. Other Cahills have held positions in politics, sport, and the arts.

In popular culture, the Cahill name is used for the central family in The 39 Clues series, a multi-author young adult adventure franchise that centers on a global mystery spanning generations.

The surname has also appeared in genealogical and onomastic studies of Irish names, reflecting patterns of migration, Anglicization, and regional distribution. Overall, Cahill remains a prominent surname in Ireland and among communities abroad, with a legacy tied to historical lineage and cultural identity.