My favorite Protestant hymn is probably “How Great Thou Art.” According to the Wikipedia article, the song is pretty recent (even for Protestant tunes), having been written by a Swede, Carl Gustav Boberg, in A.D. 1885. Wiki states that Billy Graham’s crusades popularized the song, though I wonder how well it was known in American Protestant circles before the late 1940’s.
Here is the hymn performed at the Royal Albert Hall:
I particularly like the doxastic and cosmological elements in the song.