Please specify Irish Gaelic or Scottish Gaelic: they are two separate languages.
In Irish it's "grásta"
Grásta Iontach
Taigh gràis ?
Sabhailte ag grasta
In Irish it's "grásta amháin"
In Irish it's "grásta amháin"
gràs
Is Éireannach mé trí dheonú Dé. (in Irish)
http://www2.smo.uhi.ac.uk/gaidhlig/faclair/sbg/lorg.php?faclair=sbg&seorsa=Beurla&facal=grace&eis_saor=on&tairg=Lorg
Mac na h-Alba le gràs Dè.
Yes, McGrath is a common Irish surname. It is of Gaelic origin, derived from the Irish name "Mac Craith," meaning "son of grace."