In England Ray is sometimes grouped with several other surnames - Wray, Wreay, Wragg, Rea - given a common origin, the Danish (or Norse?) VRA. This means a nook, a corner, a secluded spot, and can be found in Northern English place-names, e.g., Wreay in Cumbria. It's possible that the names without initial W could have other origins, as already suggested. The hint of a German origin could scotch all these suggestions, and lead us off in another direction.