McCann is an Irish surname derived from the Gaelic Mac Cana, meaning "son of Cana". The Cana particle is a personal name meaning 'wolf cub'.
According to Irish tradition they are descended from Brassil, a grandson of Colla-da-Chrioch, the first king of Airgialla, and as such they and their territory also became known as Clan Breasail. This territory lay to the south of Lough Neagh in modern-day County Armagh and County Tyrone, flanked by the River Bann and River Blackwater. The major family of the name McCann were known as lords of Clanbrassil, they were notably a branch of the Cenel Eoghain, the large group of families claiming descent from Eoghan, of the sons of Niall of the Nine Hostages. Amhlaoibh Mac Cana was praised for his chivalry, his vigour, and his strong drink he made from apples in his orchard. The McCanns are also stated as having had a castle at Portadown in County Armagh. The last recorded Chief of the name, Donall MaCanna, was still known as lord of Clanbrassil as late as 1598. The title of lord of Clanbrassil is still held by the family of McCann in the area of County Louth.
The McCann line features in John O' Hart's 19th century pseudo-historical book, Irish pedigrees. In this book, the McCann line along with other surname lines are taken right back to Adam and Eve.
During the years this surname has had different variations, such as MacCann, MacCan, Maccan (this part of the Maccans had connections with many European noble and royal families, such as the Maccan Romanoff or the Maccan of Villanova or Maccan de Gueldre), McCann, MacCana, and became Canny and Canney upon Ulster migration to the south (Leinster and Munster).