Family name Breffni (Breffni 
) , all around the world, is a very rare surname. The family name Breffni is habitual in Ireland, where it is a rare surname, Hungary, and the United Kingdom, where it is an extremely rare surname. Not in comparison with a country's population, this name is the most popular in Hungary, Ireland, and China. More prevalently, Breffni is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Breffni | United Kingdom, Hungary, France, Ireland, United States |