Ó Deasmhumhnaigh is a traditional Irish Gaelic surname, anglicized as Desmond. The name derives from the region of Desmond in southern Ireland, historically known as "south Munster" (from Irish Deasmhumhain). The surname originally indicated a person who hailed from that kingdom.
The Desmond region was a medieval kingdom ruled by the MacCarthy dynasty, which played a prominent role in Irish history until the Desmond Rebellions of the 16th century. The surname Ó Deasmhumhnaigh thus carries connotations of regional identity and Gaelic heritage.
Notable Anglicized bearers of the name include Desmond Tutu (1931–2021), the South African Anglican archbishop and anti-apartheid activist, although his family name derives from the same root via Irish migration.
- Meaning: "descendant of the person from south Munster"
- Origin: Irish Gaelic
- Type: Surname
- Usage: Primarily Irish
- Related forms: Desmond, deasmhumhain