Walsh (Irish: Breathnach) is a common Irish surname. It derives from a Middle English variant of the word "Welsh", and originally denoted a Welsh speaker, a number of whom arrived in Ireland following the Anglo-Norman invasion of the 12th century. It is the fourth most common surname in Ireland and the 265th most common in the United States. There are variants including "Walshe", "Welch", "Welsh", and "Brannagh" (an anglicisation of the Irish form). Walsh is uncommon as a given name. The name is often pronounced "Welsh" in the south and west of the country.
In Great Britain, Guppy encountered the name only in Lancashire. It is the surname of the Barons Ormathwaite.