Danish and Swedish pet form of Maria. It came to be used in the English-speaking world largely as a result of the fame of the actress Mia Farrow (b. 1945) and has enjoyed a sharp rise in popularity since the late 1990s.
French: from a diminutive of Old French garra ‘crock or jar for oil’, presumably a metonymic occupational name for a maker of such crocks or for a producer or seller of aromatic or comestible oils. This name is concentrated in LA.