More info about the name "Gallagher"

Gallagher is a modern version of the Gaelic name 'O' Gallchobhair'. The 'O' means 'son of' and the 'Gallchobhair' is a derivative of the words 'gall', meaning 'foreign', and the word 'cabhair', which means help. It could possibly have been a clan name for foreign mercenaries.