http://en.wikipedia.org/wiki/Brian
"Brian (Bryan) is a male forename of Celtic origin. According to Behind the name, its original meaning is not known for certain but " ... it is possibly related to the Old Celtic element bre meaning hill, or by extension high, noble. Brian Boru was an Irish king who thwarted Viking attempts to conquer Ireland in the 11th century. He was victorious in the Battle of Clontarf, but he himself was slain.".
According to Higgins and Goldner, it is of Gaelic origin and means "Honor, strength, virtue", and variants of the name include Briant, Brien, Brion, Bryan, Bryant, and Bryon."