Brian 'Breaghach' Mág Samhradháin, the Second, (anglicised McGovern) was chief of the McGovern Clan of Tullyhaw, County Cavan from 1272 to 3 May 1294.
His ancestry was Brian mac Donnchadh Cime (d. 1269) mac Giolla na Naomh (d. 1255) mac Giolla Iosa (d. 1231) mac Giolla na Naomh (fl. 1170) mac Muireadhach (fl. 1130) mac Samhradhan (fl. 1100), who were all previous chiefs of the clan. His mother was May Mór O'Ruairc, the daughter of Amlaíb O'Ruairc, king of West Breifne from 1257–1258. His brothers included Maghnus Mág Samhradháin (who succeeded to the chieftaincy on Brian's death and ruled from 1298 to 1303) and Macraith Mág Samhradháin, the ancestor of two McGovern bishops (Cormac Mác Shamhradháin of Ardagh and Cormac Mág Shamhradháin of Kilmore). Brian's nickname 'Breaghach' is the adjectival form of Brega, originally referring to a person or thing worthy of Brega, in County Meath and the Book of Magauran states he was called that because he had the three qualities of a High-King of Tara, i.e. gallantry, pride and hospitality. A less likely explanation is that it may mean he was fostered in Brega as a child.
On the death of his father Donnchadh 'Cime' Mág Samhradháin in 1269, Brian's uncle, Tomás Mág Samhradháin, succeeded as chief until his death in 1272, whereupon Brian took the chieftaincy. He soon came under pressure from the O'Reilly clan to the east and the clan Muircheartaigh Uí Conchobhair (O'Connor) to the west. In 1295 the Annals of Connacht state-
The hostages of Brian Mac Samradain and of Gilla Isa Mag Dorchaid were taken by Gilla Isa O Raigillig.
Brian then married off his daughter Gormlaidh to Matha O'Reilly (d. 1301), the son the aforesaid Gilla Isu Ruad mac Domnaill O'Reilly, chief of the O'Reilly's of East Breifne from 1293–1330.