English, Irish and Scottish from Latin "grace" or "favour" [ONC].
In Scotland, according to Whyte, Grace was derived from Gris, a diminutive for Grizel, from Old German, possibly meaning "grey battle-maiden".
Grace occurred frequently in the 1841 Census of Aberdeenshire, where several other spelling variants also occur, e.g. Gress, Gressie. Most of these should be retrieved by Soundex search.
In old documents, written in Latin, Gratia was used for Grace, with appropriate case endings.
Grania/Granya is the Latinized form of Gráinne, an Irish Gaelic name of uncertain origin. Gráinne is sometimes Anglicized as Grace which is therefore classed here as a lesser synonym of Grania/Granya.