Tolkien had a picture postcard on which he wrote "origin of Gandalf"; it was of a painting by the German artist Josef Madlener depicting a cloaked, long-bearded old man in a mountain forest petting a fawn, entitled "Der Berggeist" or The Mountain-spirit.
http://tolkiengateway.net/w/images/9..._Berggeist.jpg
In other words, pretty Germanic.