In Goidelic mythology, and especially Scotland, Brian was a bumbling fool who helped Cailleach rescue Dia Griene. He was a son of Tuireann, and brother to Iuchar and Iucharba (these have many variant spellings). The name, Brian, is of Celtic origin, and its meaning is "strong".

In Irish mythology, the sons of Tuireann murdered Cian, the father of Lugh, one of the greatest of the Tuatha Dé Danann. They also dismembered his body and tried to cover up their crime. In recompense, Lugh made them quest all around the known world as far as Persia fetching magical weapons, which Lugh planned to use at the Second Battle of Magh Tuiredh. They succeeded in obtaining all that Lugh demanded, but returned to Ireland desperately injured, pleading for Lugh to heal them; but the latter refuses. In at least one version of this tale, Brian is actually the clever and subtle one, while his brothers Iuchar and Iucharba are bumbling and easily overawed by Brian. This tale of the Sons of Tuireann has sometimes been likened to an Irish Argonautica.

'Brian' is also the name of Brian Boru, High King of Ireland, who was victorious over the Danes at the Battle of Clontarf in 1014 CE (i.e. 1014 AD).

Brian is the name of the Griffins' pet dog on the television show, Family Guy.

Life of Brian is a comedy film by Monty Python.